What kind of entity is a committee, a book group or a band? I argue that committees and other such social groups are concrete, composite particulars, having ordinary human beings amongst their parts. So the committee members are literally parts of the committee. This mereological view of social groups was popular several decades ago, but fell out of favour following influential objections from David-Hillel Ruben. But recent years have seen a tidal wave of work in metaphysics, including the metaphysics of parts and wholes. We now have the resources to rehabilitate the mereological view of social groups. I show how this can be done, and why we should bother.