What do terms such as the committee, the league, and the group of women denote? Pre-theoretically, group terms have a dual personality. On the one hand, the committee corresponds to an entity as ideosyncratic in its properties as any other object; for instance, two otherwise identical committees can vary with respect to the purpose for which they were formed. Call this aspect the group-as-individual. On the other hand, the identity of a group is at least partially determined by the properties of its members; for instance, a committee will be a committee of women just in case each of its members is a woman. Call this aspect the group-as-set. Elaborating on suggestions in Link (1984) and Lasersohn (1988), I propose that group terms in English denote atomic individuals, that is, entities lacking internal structure. In particular, it is not possible to determine the membership of a group by examining the denotation of a group term. The proposed account correctly predicts that group terms systematically behave differently semantically (as well as syntactically) from plurals such as the men and conjunctions such as John and Bill. Thus the atomic analysis advocated here stands in sharp contrast to previous proposals, including Bennet (1975), Link (1984), and Landman (1989), in which group terms are considered of a piece semantically with plurals and conjunctions. Additional arguments come from the use of names of groups as rigid designators, from the parallel between group nouns and measure nouns, and from the distribution of group terms across two dialects of English.