This paper focuses on research that has implications for two important components to self-identity: personal identity and social identity. Three questions are addressed: ( I ) How do people derive a unitary sense of self our of membership in many different social categories such as those of age, gender, race, and social class? ( 2 ) Do people respond differently when the social as opposed to the personal aspects of their identity are evoked? (3) How do people respond to collective injustice? A major theme in the results is that, although the social component of self confronts the individual with fundamental problems, the need for a shared identity motivates people to maintain this dimension of self despite the problems it generates.Picture two lovers having dinner by candlelight in a quaint restaurant. By any definition this would be described as an interpersonal interaction, where the focus is on the personal and unique characteristics of the particular man and woman in the interaction. But what if the man were to inadvertently make a chauvinistic remark? The woman might well feel the need to respond as a representative of all women. She might even express opinions that she does not endorse personally because at the moment she feels an obligation to represent the majority of women. The man would then become defensive and feel the need to defend himself as a man. Indeed, if the debate were to escalate, others in the restaurant might well be treated to an unanticipated public spectacle.This little scenario contains a number of elements that are central to the theme of this volume in general. Specifically, the focus is on cells B and D in