In contrast to traditional approaches that widely equate group cohesiveness with interpersonal attraction, self-categorization theoryargues that self-categorization depersonalizes perception in terms of the group prototype, and transforms the basis of interindividual attitude (liking) from idiosyncracy into prototypicality. An implication is that while attraction in interpersonal relationships relates to overall similarity, attraction among group members is based on prototypical similarity. To test this idea, subjects (N = 219) participated in an experiment in which they reported their attitude towards an individual who would be their partner, or a fellow group member (of either group ‘Visual’ or group ‘Tactile’) for a subsequent task. Subject-target similarity varied on each of two dimensions: dimension ‘A’ was more prototypical of group ‘Visual’, and dimension ‘F’ of group ‘Tactile’. The independent variables of social orientation (interpersonal, group ‘Visual’, group ‘Tactile’), similarity on dimension A (A ±), and dimension F(F±) were manipulated in a 3 × 2 × 2 design. The three hypotheses tested in this experiment were generally supported. Subjects preferred prototypically similar group members to interpersonal partners, and downgraded prototypically dissisimilar group members (HI). Identification was positively related to target evaluation (H2), more strongly for prototypically similar than dissimilar targets (H3), and the identification-attraction relationship was mediated by perceived prototypical similarity. Group-based effects were independent of perceptions of overall similarity.