Summary

Partisanship remains a powerful influence on political behavior within developed and developing democracies, but there remains a lively debate on its nature, origins, and measurement. In this debate, political scientists draw on social identity theory to clarify the nature of partisanship and its political consequences in the United States and other developed and developing democracies. In particular, social identity theory has been used to develop an expressive model of partisanship, which stands in contrast to an instrumental model grounded in ideological and policy considerations. Included here are a discussion of the key motivational and cognitive components of social identity theory and an explanation of how the theory can be applied to the study of partisanship. The focus is on the measurement of partisanship, its social nature, its origins in convergent identities, and its ability to generate strong emotions and drive political engagement. Lastly, areas for future partisanship research are discussed. These areas include the study of negative partisan identities, coalitional identities in multiparty systems, and the political situations in which expressive and instrumental aspects of partisanship are most common.