Groups and solidarity are, separately, widely debated concepts in contemporary social philosophy, yet their interplay remains largely unexplored and undertheorized. In fact, when it comes to investigating one of these concepts, more often than not the other is at best vaguely mentioned as a background assumption, and vice versa. This issue aims to foster a discussion of groups and solidarity as intimately related subjects, and this proposal is addressed to the domain of social philosophy. However, it is also intended to highlight some peculiar features that both discussions own independently, which could provide a preliminary groundwork for bridging the gap.