This chapter examines the role of experimentation within the social identity approach to the study of identity. The main question of interest concerns the ways in which experimental methods give particular shape to how identity is understood within this tradition. We will examine the historical, theoretical, and practical development of the social identity approach and of experimentation in psychology, and then show how the two have converged so as to create an insightful, and yet simultaneously limited and at times even problematic, understanding of identity. This particular constellation of theoretical assumptions and practical methods has produced an impressive body of important research. It has also led to the establishment and entrenchment of theoretical and methodological biases of which researchers often seem to be unaware, but which nevertheless considerably influence the study of identity within the social identity tradition. Thus, in light of the rich output of the social identity approach, the chapter examines some of the limitations of that tradition and attempts to draw researchers’ attention to the theoretical and methods-based biases of which they may not be aware. In this way, the chapter is an attempt to explore how experimental methods and theory have interacted within the social identity tradition to both the benefit and detriment of our understanding of identity.