Three studies examined perceptions of the entitativity of groups. In Study 1 (U.S.) and Study 2 (Poland), participants rated a sample of 40 groups on 8 properties of groups (e.g., size, duration, group member similarity) and perceived entitativity. Participants also completed a sorting task in which they sorted the groups according to their subjective perceptions of group similarity. Correlational and regression analyses were used to determine the group properties most strongly related to entitativity. Clustering and multidimensional scaling analyses in both studies identified 4 general types of groups (intimacy groups, task groups, social categories, and loose associations). In Study 3, participants rated the properties of groups to which they personally belonged. Study 3 replicated the results of Studies 1 and 2 and demonstrated that participants most strongly valued membership in groups that were perceived as high in entitativity.