​Sociologists have turned to collective identity to fill gaps in resource mobilization and political process accounts of the emergence, trajectories, and impacts of social movements. Collective identity has been treated as an alternative to structurally given interests in accounting for the claims on behalf of which people mobilize an alternative to selective incentives in understanding why people participate, an alternative to instrumental rationality in explaining what tactical choices activists make, and an alternative to institutional reforms in assessing movements’ impacts. Collective identity has been treated both too broadly and too narrowly, sometimes applied to too many dynamics, at other times made into a residual category within structuralist, state-centered, and rationalist accounts.