The term “identity” first took the stage in Reformation studies with the publication of Young Man Luther (1958), in which psychologist Erik Erikson framed the reformer’s life and work in terms of identity crises. By the early 1970s, however, the concept had acquired such a wide range of meanings and connotations that many historians grew wary of using it. This lecture explores how constructivism helped “identity” regain its usefulness for the study of religious history. Beginning in the 1980s, scholars started to wonder how long it might have taken for ordinary people to identify with confessional categories—generating new approaches to the role of lay believers in processes of religious change. Judith Pollmann considers how and why this new work was particularly useful for the histories of France and the Low Countries, before finally considering what the concept of “identity” might yet achieve.