The concept of identity has become increasingly prominent in the social sciences and humanities. Analysis of the development of social identities is an important focus of scholarly research, and scholars using social identities as the building blocks of social, political, and economic life have attempted to account for a number of discrete outcomes by treating identities as causal factors. The dominant implication of the vast literature on identity is that social identities are among the most important social facts of the world in which we live. Abdelal, Herrera, Johnston, and McDermott have brought together leading scholars from a variety of disciplines to consider the conceptual and methodological challenges associated with treating identity as a variable, offer a synthetic theoretical framework, and demonstrate the possibilities offered by various methods of measurement. The book represents a collection of empirically-grounded theoretical discussions of a range of methodological techniques for the study of identities.