What is it like to be a part of a group? What do “We” have in common, and how do “We” differ from “Them?” How do our perceptions of and memories about the ingroup and the outgroup vary as a function of being in this group or that group? A central theme in the evidence described below is that the relative sizes of the ingroup and the outgroup will determine the distinctiveness of one group relative to another. In other words, guiding the research described in this chapter is the definition of distinctiveness as the increase in salience or attention afforded to a social group as a function of its relative numerical rarity: the smaller group is more distinctive. The notion that relative group size may be a central structural or topographical determinant of group processes is not a new idea. This chapter also discusses group composition and self-focused attention, distinctiveness and perceptions of variability, stereotyping, distinctiveness and memory for a token's behavior, and a model of the phenomenology of being in a group.