This article investigates the relationship between levels of party institutionalization and individual-level partisan mobilization. Levels of party institutionalization have been linked to macro-level outcomes such as party system stability, but little is known about the micro-level underpinnings of such patterns. This article investigates one set of mechanisms through which party institutionalization might affect electoral outcomes. Specifically, we ask how routinization and value infusion – two central dimensions of party institutionalization – shape partisans’ political mobilization. We investigate these relationships by matching data on individual-level behaviour (taken from the International Social Survey Program (ISSP) 2014 wave) with data on party attributes commonly associated with levels of institutionalization (taken from the Democratic Accountability and Linkages Project – DALP). We find that while value infusion encourages relatively greater participation from non-member supporters, party routinization depresses non-member participation but may mobilize otherwise inactive members. These findings suggest that to understand the effects of party institutionalization on a macro-level phenomenon such as electoral volatility, it may be necessary to study how parties institutionalize, rather than just asking how much they institutionalize.