A desire to create "we the people" is something all integration projects across time and space profess, yet we still know little about how these superordinate identities are actually formed and what causes variation in individuals' propensity to adopt them. Given an overarching, cohesive identity's purported ability to ease intergroup tension and bolster support for the political system, it is crucial that scholars isolate the factors that promote or hinder its emergence. My dissertation, "Cultivating the Collective: Identity Choice in Europe," investigates why individuals choose to identify a certain way in the presence of multiple identity alternatives. Combining institutional analysis with a social-psychological framework, Part I probes the extent to and ways in which government institutions affect citizens' identity inclinations. I find that exposure to EU institutions bolsters supranational identification with Europe by increasing EU knowledge, trust, and political interest while mitigating the negative effects of national pride and perceived cultural threat. Part II delves into subnational attachments, finding that identifying with the region more than the nation decreases EU support. This effect is exacerbated under conditions of high regional authority, suggesting that regional identity only matters where institutional structures exist to politicize it. Part III (in progress) reevaluates assumptions drawn from the American context about how different types of identity affect a host of attitudinal and behavioral outcomes. Finally, Part IV (Spring 2012) will analyze the determinants of immigrants' identity choice using original survey data from the UK and Ireland to gauge their level of psychological assimilation.