Literature Review

A large body of research has examined the relationship between education and support for the EU, providing a clear empirical picture: lower levels of education are associated with less support for the EU. More specifically, numerous empirical studies have shown that less highly educated citizens are less supportive of EU membership (for example Anderson and Reichert Reference Anderson and Reichert1996; Dellmuth and Chalmers Reference Dellmuth and Chalmers2018; Hakhverdian et al. Reference Hakhverdian2013; Kuhn et al. Reference Kuhn2016, Lubbers and Scheepers Reference Lubbers and Scheepers2010), are less in favour of further European integration (for example, Beaudonnet Reference Beaudonnet2015; Gabel Reference Gabel1998; Gabel and Palmer Reference Gabel and Palmer1995; Hooghe and Marks Reference Hooghe and Marks2005; McLaren Reference McLaren2002), and have less trust in EU institutions (for example Foster and Frieden Reference Foster and Frieden2017; Lipps and Schraff Reference Lipps and Schraff2020; Sani and Magistro Reference Sani and Magistro2016).

The literature offers three main explanations to account for the positive relationship between education and EU support, which are economic, political, and cultural in nature. First, the economic explanation centres around the ‘left-behind thesis’ (initially formulated by Gabel Reference Gabel1998; Gabel and Palmer Reference Gabel and Palmer1995). According to this perspective, individuals with lower levels of education are those who lose out in the context of European integration, since education is positively correlated with potential benefit from greater integration. Based on the premise that certain individual skills are more valuable and transferable in a supranationally integrated economy than others, the left-behind thesis claims that those with higher educational attainment and more marketable occupational skills are better prepared to apply their talents in diverse international settings and to adapt to economic changes in their production sector or region. Consequently, the economic costs and benefits related to European integration are asymmetrically distributed between individuals with different levels of education, with highly educated citizens being regarded as the main beneficiaries, as they have the largest ability to capitalize on the new opportunities presented by an integrated European economy. This perspective aligns with research demonstrating that individuals with higher levels of education tend to perceive greater personal benefits from EU membership (McLaren Reference McLaren2007) and exhibit notably lower concerns about European integration posing a threat to the domestic labour market than their lower-educated counterparts (Baute et al. Reference Baute2018; Grauel, Heine, and Lahusen Reference Grauel, Heine, Lahusen, Arts and Halman2013).

Second, political explanations have underscored the role of supply-side actors such as political parties and the news media. Given citizens' limited familiarity with and exposure to EU institutions, they often rely on political cues from the domestic political arena and the media as convenient shortcuts for obtaining information about the EU (Anderson Reference Anderson1998). In particular, individuals with lower levels of education are more likely to possess lower levels of political awareness and EU knowledge compared to their more educated counterparts, making them more prone to follow the party and media cues of Eurosceptic voices (Hobolt Reference Hobolt2005; Schuck and De Vreese Reference Schuck and De Vreese2006).

Third, cultural explanations have honed in on the significance of national identity, perceptions of ethnic threat, and cosmopolitan attitudes. According to this cultural perspective, lower-educated individuals are less supportive of the EU because they have a less cosmopolitan worldview and perceive the EU as a threat to their national identity (Inglehart Reference Inglehart1970). Numerous empirical studies corroborate that identity concerns are particularly pronounced among those with lower levels of education (for example Lubbers and Jaspers Reference Lubbers and Jaspers2011; McLaren Reference McLaren2003), and these concerns are consistently linked to lower levels of support for the EU (Carey Reference Carey2002; Hooghe and Marks Reference Hooghe and Marks2005; McLaren Reference McLaren2002; Teney, Lacewell, and De Wilde Reference Teney, Lacewell and De Wilde2014).

Moreover, providing important nuance to the well-established positive association between education and EU support, a limited number of studies have explored the temporal dynamics of this relationship. These contributions reveal a discernible trend of growing educational divergence in EU approval over time (Hakhverdian et al. Reference Hakhverdian2013; Lubbers and Jaspers Reference Lubbers and Jaspers2011; Sani and Magistro Reference Sani and Magistro2016). Hakhverdian et al. (Reference Hakhverdian2013) draw on Eurobarometer data from 1973 to 2010 in twelve EU countries and find that the positive correlation between the level of education and support for the EU has grown stronger after the signing of the Maastricht Treaty. Similarly, Lubbers and Jaspers (Reference Lubbers and Jaspers2011), using longitudinal data from a Dutch panel, report that the educational divide in Euroscepticism increased between 1990 and 2008. The authors attribute this trend primarily to an increasing sense of cynicism towards politics and a heightened perception of ethnic threat among individuals with lower levels of education. Finally, Sani and Magistro (Reference Sani and Magistro2016) analysed European Social Survey data from 2002 to 2012 in twenty European countries. The results of this study suggest that while trust in the European Parliament experienced an overall decline after the economic crisis of 2008 and 2009, this decline was particularly pronounced among less educated individuals.

Institutional Integration and the Educational Divide in EU Support

The preceding literature review indicates that the educational divide in EU support is the result of economic, political, and cultural factors. Furthermore, it highlights that this educational divide has expanded over time, coinciding with the increasing prominence of these factors. Yet, why have these economic, political, and cultural influences become more salient? Is there a common, EU-specific underlying reason, or do these trends simply mirror (global) temporal dynamics? In this article, we argue that the long-term process of European institutional integration is a pivotal yet largely neglected explanation. Before expanding our reasoning, it is important first to clarify what we mean by European institutional integration. In general terms, the 1957 Treaty of Rome can be seen as the official starting point for institutional integration in Europe, when six countries founded what was then called the European Economic Community (EEC) and has since gradually developed into today's twenty-seven-member European Union. The empowerment of core bodies such as the European Commission and the European Court of Justice, together with the latest modifications laid out in the Treaties of the European Union, has increasingly pooled the national sovereignty of EU countries. Progressive institutional integration has resulted in the current multi-level governance system, in which decision-making is shared between national governments and EU institutions (Pierson and Leibfried Reference Pierson, Leibfried, Leibfried and Pierson1995). In fact, the relative importance of institutions distinguishes European integration from globalization, as the latter is driven by a broader range of factors and processes, including technological advancement and innovations in financial markets (Krieger-Boden and Soltwedel Reference Krieger-Boden and Soltwedel2013, 1428).

In more specific terms, however, we build on Balassa's (Reference Balassa1961) classical account and understand by institutional integration all institutional ‘measures designed to abolish discrimination between economic units belonging to different national states’ (ibid., 1). Balassa distinguished five distinct but interrelated stages of regional integration which can be applied in the case of the EU. First, a free-trade area is formed, abolishing internal tariffs and quotas among member countries. Second, a customs union establishes common external tariffs and quotas. Third, a common market eliminates restrictions on internal factor movements. Fourth, an economic union leads to a significant degree of policy coordination and legal harmonization. Fifth and finally, total economic integration is achieved, with economic policies determined and implemented at a supranational level.

Balassa's perspective on regional integration has proved remarkably prescient in the context of European institutional integration, the development logic of which has closely followed the Balassa steps (Sapir Reference Sapir2011). After the EEC institutionalized a free trade area and thus removed internal trade barriers in 1958 (first stage), the Customs Union of 1968 determined common rules for trade with non-members (second stage). Next, measures were introduced to fully liberalize the movement of goods, services, capital, and workers, reaching an institutional high point in the form of the Single European Act of 1986 and the launch of the European Common Market in 1993 (third stage). European institutional integration has also aimed to co-ordinate national macroeconomic policies (fourth stage). An important historical example of this is the introduction of the EMS in 1979, which linked the currencies of participating countries through the European Exchange Rate Mechanism (ERM) in order to prevent monetary instability. Moving beyond mere coordination, further institutional steps have been taken to address macroeconomic policy at the supranational level (fifth stage), exemplified by the establishment of the Economic and Monetary Union (EMU) in 1999. This decision, which introduced the euro as a common currency and created the European Central Bank (ECB), is arguably the most significant milestone in the history of European institutional integration.

Thus, from the beginning, the primary focus of European institutional integration has been to promote economic integration (Agur, Dorrucci, and Mongelli Reference Agur, Dorrucci and Mongelli2007; Moravcsik Reference Moravcsik1999).Footnote ¹ The specifically economic nature of European institutional integration has been described in terms of an asymmetry between ‘negative integration’ and ‘positive integration’ (for example Leibfried Reference Leibfried, Wallace, Wallace and Pollack2015; Scharpf Reference Scharpf and Marks1996; Scharpf Reference Scharpf1999; Scharpf Reference Scharpf2010). While negative integration is a market-making process aimed at the removal of economic barriers, positive integration refers to measures intended to correct negative market effects, for instance in the form of labour market regulations. As described above, the process of European institutional integration has heavily prioritized market-making over market-correcting efforts. Indeed, to date, the EU has not developed a strong social dimension that could act as a counterweight to negative integration (Ferrera Reference Ferrera, Vandenbroucke, Barnard and de Baere2017). This asymmetry means that European institutional integration has progressed in a way that is particularly beneficial to the highly educated, who are likely to thrive in a European system of increasingly integrated markets. By contrast, the interests of less highly educated individuals are largely unaddressed in this process, making concerns and fears about the EU more likely to grow within this section of the population.

Moreover, as a result of progressive European institutional integration since the 1950s, EU institutions have become more salient to European citizens over time. While European integration was once a non-issue for the general public, and European elections were mere popularity tests for national governments (Reif and Schmitt Reference Reif and Schmitt1980), the issue has become increasingly relevant to many voters (Hobolt, Spoon, and Tilley Reference Hobolt, Spoon and Tilley2008). Researchers have labelled this a shift from ‘permissive consensus’ – where citizens agreed with elites when it came to the pooling of sovereignty – to ‘constraining dissensus’ (Hooghe and Marks Reference Hooghe and Marks2008). Hooghe and Marks (Reference Hooghe and Marks2008, 13) claim that the scope and depth of European integration have perceptibly increased and their effects have been magnified because these effects are part of a broader breakdown of national barriers giving rise to mass immigration and intensified economic competition. A noticeable sign of the waning permissive consensus was the decrease in support for the EU after the Maastricht decision on the EMU, commonly referred to as the ‘post-Maastricht blues’ (Eichenberg and Dalton Reference Eichenberg and Dalton2007; Guinaudeau and Schnatterer Reference Guinaudeau and Schnatterer2017).

Taking these concurrent processes into account, we argue that European institutional integration widens the educational divide in support for the EU. At the beginning of the institutional integration process, the EU was a relatively vague, un-institutionalized project that was broadly aimed at promoting peace and prosperity in post-war Europe. This arguably explains the high levels of public support for European integration in its early developmental stages (see Anderson and Hecht Reference Anderson and Hecht2018). However, with the expansion of European institutions, their specific economic impetus, with its asymmetric benefit structure, has become more and more apparent. Thus, we expect that the implications of the economic left-behind thesis for EU support should increasingly manifest in line with increasing European institutional integration. Specifically, we expect that the highly educated – who benefit most from progressive integration – will continue to express high levels of support for the EU, whereas individuals with lower levels of education become increasingly sceptical or even opposed to the EU.Footnote ²

In addition, we posit that the same rationale extends to arguments linking political and cultural factors with the educational divide in EU support. As EU institutions grow in significance, disparities in political and cultural beliefs among educational groups are likely to play a more significant role in shaping levels of support for the EU. For instance, the institutionally guaranteed freedom of movement of workers likely magnifies how political and cultural perceptions affect EU support across educational lines. While individuals with higher education levels may perceive the free movement of workers as an opportunity for economic growth, international cooperation, and cultural exchange, those with lower education levels, often relying on political cues from Eurosceptic anti-establishment parties, might increasingly perceive the EU project as a threat to the domestic labour market, national sovereignty, and cultural identity (take the Brexit vote as a case in point, for example, Hobolt Reference Hobolt2016).

Thus, in short, we propose the following hypothesis:

Empirical Strategy

In order to test our theoretical argument empirically, we require three pieces of information: (1) long-term data on individual support for the EU, (2) corresponding details of individuals' levels of education, and (3) a measure that captures the extent of European institutional integration in member states over time. Based on these data points, we attempt to model statistically how support for the EU is shaped by individual educational attainment and whether this relationship varies with the existing degree of institutional integration in the country of an individual's residence.

Measurement

Support for European integration

We measure individual support for the EU using data from the European Commission's Eurobarometer survey. Pooling all eighty-five relevant waves covering the EU-15 (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain, Sweden, and the United Kingdom) between 1976 and 2014,Footnote ³ we draw on the following survey item: Generally speaking, do you think that (your country's) membership of the European Community/European Union is (1) a good thing, (2) neither good nor bad, or (3) a bad thing? We turn the three response categories into a binary variable, with a value of 1 indicating support for the EU and a value of 0 indicating indifference or disapproval.

This item has been widely used as an indicator of EU support (for example Anderson and Reichert Reference Anderson and Reichert1996; Carey Reference Carey2002; Eichenberg and Dalton Reference Eichenberg and Dalton2007) and serves the purpose of our study, as it captures diffuse (regime) approval over an extensive timeframe. By contrast, more specific indicators of EU support, such as preferences on the preferred speed of European integration, are available only for shorter periods and thus impede our long-term perspective. However, acknowledging the potential multidimensionality of EU support (De Vries Reference De Vries2018; De Vreese, Azrout, and Boomgaarden Reference De Vreese, Azrout and Boomgaarden2019), we will assess the impact of using some of these shorter time series on the sensitivity of our results.

Figure 1 shows the percentage of individuals who support the EU in each EU-15 country across the entire sampling period. The data are weighted, adjusting for socio-demographic criteria and the fact that more than one sample per wave was drawn for reunified Germany (East and West Germany) and the United Kingdom (Great Britain and Northern Ireland). The graph shows that average levels of support vary widely across the EU-15, with some member states exhibiting levels of support consistently above 50 per cent (see Luxembourg and the Netherlands), while support in other countries stays consistently below this threshold (for example Austria). In addition, country-specific trends reveal substantial variation in support levels over time. In particular, a significant decline in support for European integration can be seen in many countries (for example Belgium and Germany) in the 1990s, reflecting public discontent with the Maastricht Treaty, a phenomenon – as mentioned above – known as the post-Maastricht blues (see Eichenberg and Dalton Reference Eichenberg and Dalton2007).

Figure 1. Percentage of individuals supportive of the EU in the EU-15, 1976–2014 (weighted data).

European institutional integration

European integration is characterized by its geographically concentrated nature and its historical progression, driven primarily by institutional advancement (Krieger-Boden and Soltwedel Reference Krieger-Boden and Soltwedel2013). To measure the precise degree of institutional progress, an additive index of institutional participation by countries at the European level has been developed at the ECB (Dorrucci et al. Reference Dorrucci2002). This index meticulously accounts for institutional changes by assigning scores to each (economically) relevant event of European institutional integration from the inception of the European Community in 1957 onwards. These events are grouped into the five Balassa stages of regional integration (Balassa Reference Balassa1961), which closely reflect the historical institutional development of the EU as discussed in the section ‘Institutional integration and the educational divide in EU support’.

To illustrate how the index works, we provide a few examples that show how it scores significant institutional events in each of the five stages. For instance, the index considers the abolition of quotas (index score of 4) a crucial event for forming a free-trade area (first stage) and completing the customs union (second stage). Moreover, the directive of 1988 requiring full liberalization of capital movements (index score of 5) is understood as a seminal event in establishing a common market (third stage). As another example, the launch of the EMS in 1979 (index score of 4) enters the index as an important development in building an economic union (fourth stage). Finally, introducing a single monetary and exchange rate policy in 1999 (index score of 5) is seen as a key event on the way to total economic integration (fifth stage). More details on the measurement criteria, indicators, and scores used to construct the index can be found in Dorrucci et al. (2002, 33–41).

The first version of the index included only the six founding members but was later expanded to incorporate the remaining nine EU-15 countries that joined the EU between 1973 and 1995, covering the years from 1957 to 2004 (Dorrucci et al. Reference Dorrucci2005). Krieger-Boden and Soltwedel (Reference Krieger-Boden and Soltwedel2013) revised the index by time-smoothing data over accession periods and taking into account pre-accession membership of the European Free Trade Association as well as exemptions of some acceding countries, such as Denmark and the UK, from the Schengen Area and the EMU. More recently, Tober (Reference Tober2022) updated the index for the years from 2005 to 2014 based on another ECB index capturing the most economically important institutional integration events over this period (for this ECB index, see Dorrucci et al. Reference Dorrucci2015). An example of an important event of institutional integration in this period is the establishment of the Single Supervisory Mechanism that was implemented in 2014 as part of the European Banking Union (index score of 2).

Based on this updated index, Figure 2 plots the level of European institutional integration in each EU-15 country between 1957 and 2014. The light lines in the background of each panel indicate the trends in other countries. The graph clearly shows the institutional head start enjoyed by the six founding member states (Belgium, France, Germany, Italy, Luxembourg, and the Netherlands) in the early decades of European integration compared to countries that joined the EU in later years. Although the six founding members commonly exhibit the highest levels of institutional integration at given points in time, moments also appear where one or other of the founding countries falls slightly behind their peers, for instance when France withdrew from the ‘currency snake’ in 1974 or when Italy abandoned the rules of the ERM in 1992. Such cases of reversed institutional integration highlight the non-linear and cross-nationally differentiated nature of the European institutional integration process and underscore the importance of theoretically and empirically distinguishing the effects of institutional integration from mere time dynamics.

Figure 2. European institutional integration in the EU-15, 1957–2014.

Educational attainment

To measure respondents' educational attainment, we rely on the following question from the Eurobarometer: How old were you when you finished your full-time education? The answer categories range from up to 14 years to 22 years and older. Following previous research (for example, Hakhverdian et al. Reference Hakhverdian2013; Kuhn et al. Reference Kuhn2016), we transform this scale into a three-item categorical variable where low educational attainment stands for those who finished their education at fifteen years of age or younger, medium represents those finishing their full-time education at sixteen to nineteen years old, and high covers all respondents who were twenty or more years old when they finished education. These intervals roughly correspond to the completion of lower secondary, upper secondary, and tertiary education. We exclude those individuals who are still studying due to our (partial) focus on the labour market returns of education.

This measure of education is admittedly crude and has two major shortcomings. Firstly, it may not fully capture differences in schooling intensity, as variations in starting ages of compulsory education across countries and potential gap years in educational trajectories are not considered. Secondly, the uniform duration of different types of educational programmes within and across countries masks qualitative distinctions between qualifications, resulting in differences in competencies and labour market value. However, research also suggests that the duration of schooling is strongly correlated with other education indicators (Schröder and Ganzeboom Reference Schröder and Ganzeboom2014). Therefore, while our choice is partly influenced by a lack of alternatives in the Eurobarometer, we contend that this measurement approach serves as an acceptable proxy for the level of education.

Figure 3 plots the percentage of individuals supportive of the EU against the level of European institutional integration conditional on our three categories of educational attainment. The data are pooled across space and time; thus, a dot can refer to multiple countries and years (all the country-year observations at that particular value of European institutional integration). This descriptive exercise provides supporting evidence for our argument that deepening levels of institutional integration are associated with larger educational divides in support for the EU. While levels of EU support among the highly educated remain relatively stable as institutional integration progresses, the relationship becomes increasingly negative as we move to medium and low levels of education, which suggests that higher institutional integration reduces EU support, in particular, among less highly educated citizens. However, this descriptive analysis does not control for alternative explanatory factors nor does it account for potential country- and time-specific variation. Specifically, relying solely on Figure 3 makes it challenging to determine whether the observed correlation is a result of European institutional integration or an inherent time-related pattern. Thus, our modelling approach will address these issues in detail below.

Figure 3. Percentage of individuals supportive of the EU conditional on European institutional integration and educational attainment (weighted data).

Control variables

In the subsequent regression analysis, we consider a series of additional explanatory factors that might influence support for the EU at both the individual and country levels. At the individual level, we rely on additional variables from the Eurobarometer surveys to account for respondents' age, gender, marital status, self-placement on a political Left-Right scale (ranging from 1 = Left to 10 = Right), and whether or not they are unemployedFootnote ⁴ or retired. Another potentially important individual determinant of support for European integration is income. However, we do not control for income for two reasons. First, the Eurobarometer does not measure income in a consistent manner that would allow between- and within-country comparisons, as the applied income categories vary between countries and survey waves. Second, and more importantly, conditioning on income would cause overcontrol bias (see Elwert and Winship Reference Elwert and Winship2014), as education is a crucial determinant of income and thus controlling for income would impede the identification of the causal effect of education on support for the EU.

At the country level, we control for the annual level of unemployment (obtained from the AMECO database) as a measure of the overall socio-economic situation of a country, annual social security transfers as a percentage of GDP (obtained from the OECD National Accounts Statistics database) as a measure of the generosity of the welfare state, and the annual degree of globalization as captured by the KOF Globalisation Index (Gygli et al. Reference Gygli2019) as an alternative cause of structural change in the observed period.

Statistical specification

To model the impact of education and European institutional integration on support for the EU, we estimate Bayesian logistic mixed models. The regression formula is given by:

$$\eqalign{& {\rm Respons}{\rm e}_{ict}\sim {\rm Bernoulli}\;( P( {\rm Suppor}{\rm t}_{ict}) ) \cr {\rm logit}\;( P( &{\rm Suppor}{\rm t}_{ict}) ) = {\rm Educatio}{\rm n}_{ict}\beta _1 + {\rm Integratio}{\rm n}_{ct}\beta _2 + ( {\rm Educatio}{\rm n}_{ict}\cdot {\rm Integratio}{\rm n}_{ct}) \beta _3 \cr & \hskip5pc{ + } {{x}^{\prime}}_{ict}\lambda _1 + {{z}^{\prime}}_{ct}\lambda _2 + {\rm Country}_{c-1}^{\rm ^{\prime}} \lambda _3 + \eta _t + \xi _{ct} + \psi _\alpha + {\rm \epsilon }_{ict} \cr & \hskip-2pc\beta _1, \;\beta _2, \;\beta _3, \;\lambda _1, \;\lambda _2, \;\lambda _3\sim {\rm Normal}\;( 0, \;1) \cr & \hskip3pc\eta _t, \;\xi _{ct}\sim {\rm Student}\;( 4, \;\,0, \;\,1) \cr & \hskip4.2pc\psi _\alpha \sim {\rm Student}\;( 3, \;\,0, \;\,2.5) } $$

where Response_ict is the binary response of individual i from country c at time t to the Eurobarometer question asking whether European integration in one's country is a good ( = 1) or a neutral/bad ( = 0) thing. P(Support_ict) is the probability that an individual considers the EU a good thing, which we constrain to the probability space between 0 and 1 using the logit-link function. On the right-hand side of the regression equation, Education_ict is the individual's level of education (low, medium, or high), Integration_ct is the degree of European institutional integration in country c at time t, and (Education_ict ⋅ Integration_ct) is the interactive term between these two variables of interest. We expect the corresponding coefficient β ₃ to be positive, signalling an increasing divide along educational lines as European institutional integration progresses.

In addition, $x_{ict}^{\rm ^{\prime}}$ and $z_{ct}^{\rm ^{\prime}}$ are vectors of individual- and country-level controls, $\psi _\alpha$ is the grand mean of all responses across time and space, and $\epsilon _{ict}$ is the error term. To account for the cross-classified structure of the data, that is countries measured over time with different respondents at each time point, we include country-fixed slopes (Country_c − 1^′) as well as variance components for years (η _t) and country-years (ξ _ct).Footnote ⁵ This structure allows us to distinguish the effect of European institutional integration from general time-related patterns and mitigates the influence of other country- and time-specific factors, such as the changing composition in the level of education over time due to an increasing share of highly educated individuals.

We estimate these parameters in a Bayesian framework based on 5,000 Markov chain Monte Carlo iterations (of which 2,000 are discarded as burn-in to ensure better posterior approximation) using the brms package in R (Bürkner Reference Bürkner2017). The Bayesian approach handles complex inference problems effectively (Jackman Reference Jackman2009) and tends to produce conservative results in non-linear hierarchical models with a small number of groups and cross-level interactions (Stegmueller Reference Stegmueller2013). We put normal priors with mean 0 and a standard deviation of 1 on all population-level effects. Since our full sample consists of 822,430 complete observations (820,688 when country-level controls are included), this prior will be easily overcome by the data. For the variance components, we follow the recommendation by Gelman (Reference Gelman2006) and Gelman et al. (Reference Gelman2008) and apply weakly regularizing priors from the half-student-t family. Finally, to improve convergence and enhance comparability between regression coefficients from binary and continuous variables, we centre the latter and scale them by two times their standard deviation (Gelman Reference Gelman2007).

Concluding Discussion

How can we explain the growing educational divide in support for the EU over time? This article has argued that the historical process of European institutional integration is itself a crucial and so far overlooked factor behind this trend. Drawing on eighty-five waves of the Eurobarometer survey (1976–2014) and applying a Bayesian mixed-effects modelling approach, we have found that progressive institutional integration substantially widens the educational gap in support for the EU. Specifically, our findings show that citizens with low and medium levels of education become increasingly less supportive of the EU as institutional integration progresses, whereas the highly educated remain strongly in favour of the EU. Thus, as institutional integration advances, education assumes a progressively important role in shaping EU support. We explain this by arguing that European institutional integration leads to an increasingly bifurcated perception of the economic, political, and cultural implications of the EU between individuals with lower and higher levels of education.

A limited number of preceding studies have also indicated that the impact of education on support for the EU has intensified over time, which is attributed to the heightened significance of economic, political, and cultural factors (Hakhverdian et al. Reference Hakhverdian2013; Lubbers and Jaspers Reference Lubbers and Jaspers2011; Sani and Magistro Reference Sani and Magistro2016). However, the reasons behind the increased salience of these influences remained unclear; in particular, whether there exists an EU-specific underlying cause for this trend or if it merely mirrors broader global temporal dynamics. Distinguishing between an institutional effect and a mere time effect is crucial, as the trajectory and speed of European institutional integration is the result of concrete political decision-making and institutional reforms.

We believe that these insights yield wider policy implications. If institutional integration itself triggers Euroscepticism among low and medium educated individuals, this signals challenges for the democratic legitimacy of the EU. How can this dilemma be overcome? While the results of our explorative event study suggest that simply reversing European institutional integration may not be a solution to this problem, our findings do not necessarily imply that winning the support for the less highly educated is an impossibility. For instance, developing a stronger social dimension of European integration could have the potential to slow down or reverse the widening educational divide in support for the EU, provided that a stronger ‘Social Europe’ shifts citizens' perceptions of the EU as an elite project towards a view of the EU as benefiting wider sections of society. In this regard, existing research suggests that less highly educated citizens are indeed more in favour of EU-level social policy initiatives than the highly educated (Baute and Meuleman Reference Baute and Meuleman2020; Baute and Pellegata Reference Baute and Pellegata2022; Gerhards et al. Reference Gerhards2019). However, as EU support is not driven exclusively by economic interests and welfare concerns, a more socially oriented EU may not be a panacea to counteract growing Euroscepticism among the lower educated.

We conclude this article by highlighting three remaining questions for future research. First, our research is unable to assess the relative importance of economic, political, and cultural factors for the educational gap in support for the EU. While a straightforward explanation for our findings is the asymmetric distribution of economic costs and benefits associated with advancing EU institutionalization, it is essential to recognize that political and cultural factors may also serve as catalysts. In this context, political entrepreneurs could potentially play a crucial role, as they have increased the salience of supranational issues in the public debate (Walter Reference Walter2021), and extant work shows that the less highly educated are more receptive to their anti-EU framing (Goodwin, Hix, and Pickup Reference Goodwin, Hix and Pickup2020). We anticipate that populist parties have experienced greater success in mobilizing less highly educated voters as institutional integration has progressed. Additionally, cultural factors, such as exclusive national identities and perceptions of ethnic threat, may have been heightened among the less educated segment of the population with the advancement of European institutional integration (cf. Lubbers and Jaspers Reference Lubbers and Jaspers2011). Therefore, future research should examine the interplay between macro-level EU institutionalization processes on the one hand and micro-level economic, political, and cultural determinants of support for the EU on the other.

A second promising direction for future research is to expand the scope of countries under investigation. In particular, it may be fruitful to examine whether institutional integration has had a similar effect on educational differences in support for the EU in its Eastern member states, which joined the EU in the enlargements of 2004 and 2007. A priori, it is not clear whether we should expect similar dynamics among these newer members. For instance, in contrast to the EU-15, the Eastern countries' late entry to the EU implies that they joined at a time of already very high levels of European institutional integration, which might attenuate the potential impact of further integration. Moreover, given that the economies of the Eastern EU members are structurally different from those of the EU-15, the potential economic benefits of progressive European institutionalization might not primarily benefit highly educated individuals, but could also accrue to the less highly educated segments of these countries' societies. Comparing educational differences in support for the EU between old and new member states should thus enhance our understanding of how and to what degree economic considerations explain the effect of progressive European institutional integration on the educational divide in public attitudes towards the EU.

Finally, our results have potential implications beyond the EU context. While we acknowledge the distinctiveness of European integration, we believe that our findings may apply to other contexts as well, including at the national level. In this regard, we consider the EU and its predominantly economically driven institutional integration process (which allows for relatively concrete predictions of who should gain and who should lose out) a significant case study, demonstrating how asymmetries between the winners and losers in progressive institutionalization affect public support for the relevant institution as a whole. Overall, the results of this study suggest that addressing disparities in perceived economic benefits, as well as political and cultural concerns among different segments of the population, is crucial for maintaining the legitimacy of any institution, irrespective of the specific context.