In this chapter, it is argued that Karl Popper was a communitarian philosopher. This will surprise some readers. Liberals often tout Popper as one of their champions. Indeed, there is no doubt that Popper shared much in common with liberals. However, it will be argued that Popper rejected a central, though perhaps not essential, pillar of liberal theory, namely, individualism. This claim may seem to contradict Popper's professed methodological individualism. Yet this paper argues that Popper was a methodological individualist in name only. In fact, methodological individualism faded from Popper's vocabulary as he moved institutions and situational analysis more firmly to centre-stage. Popper's focus on institutions and situations constitutes what is called his communitarianism. If this interpretation is correct, then theorists in the sociology of scientific knowledge and communitarian epistemology should reconsider their long-standing distrust of Popper's philosophy. Indeed, they may have much to gain by treating Popper as a friend rather than a foe.