Philosophical debates about collective scientific knowledge concern two distinct theses: (1) groups are necessary to produce scientific knowledge, and (2) groups have scientific knowledge in their own right. Thesis (1) has strong support. Groups are required, in many cases of scientific inquiry, to satisfy methodological norms, to develop theoretical concepts, or to validate the results of inquiry as scientific knowledge. So scientific knowledge-production is collective in at least three respects. However, support for (2) is more equivocal. Though some examples suggest that groups have scientific knowledge independently of their individual members, these cases are also explained in terms of relational complexes of members’ beliefs.