Why do states choose informal organizations to govern global challenges? Using the global development regime as a piloting case, this article argues that different informal organizations serve different purposes. Informal intergovernmental organizations generate “club benefits” for member states, which arise from executive policy coordination behind closed doors. In contrast, transnational governance initiatives allow states to reap “risk-sharing benefits” in the production of global public goods by involving stakeholders. Using regression analysis for a set of development-related institutions, the analysis demonstrates that the two types of organizations are driven by different motivations. Complementary evidence is provided through case studies of two institutions: The IBSA Dialogue Forum (an informal intergovernmental organization) and the Global Partnership for Effective Development Cooperation (a transnational public-private partnership). The findings inform conceptual discussions of the informality of institutions while contributing to a better understanding of the design determinants of informal organizations.

We assess the development of informality in international climate policy on two levels: Whether informal organizations meaningfully contribute to climate change mitigation, and what role informality plays under the UN Framework Convention on Climate Change (UNFCCC). Proliferation of informal intergovernmental organizations (IIGOs) has enabled the move from a rigid list of countries with and without commitments, to the Paris Agreement, under which each country contributes to mitigation. Within the UNFCCC process, we find a “formality-informality cycle,” in which actors sometimes render rules and procedures more flexible and hence more efficient, only to suddenly reverse this trend at other times. Such a high-profile reversal occurred in Copenhagen in 2009. Subsequently, through the use of highly transparent negotiation procedures, trust in informality increased again, allowing negotiators to successfully override Nicaragua’s opposition in Paris in 2015. Similar formality-informality cycles can be observed on specific topics within the UNFCCC negotiations, such as international market mechanisms.

Understanding contemporary global governance requires a focus on informality. States increasingly govern through informal intergovernmental organizations, transnational public–private governance initiatives, and other informal institutions. Even within formal institutions, informal practices complement or override formal rules. And diverse informal groupings operate in the orbit of governance institutions, framing novel issues and placing them on policy agendas. We address these three aspects of informality – of, inside, and around global governance institutions. We first trace the nature and extent of the shift toward informal governance. We then consider a range of factors that may be driving the shift, drawing on major streams of International Relations (IR) theory; we treat these as candidate explanatory variables. Finally, we summarize the findings on those variables, and other theoretical insights, from the empirical chapters of this volume.