Few concepts in the depth-psychological canon bear as heavy a theoretical freight as ‘group.’ The literature moves along three broad axes, each generating its own tensions. First, the ontological question: is the group a genuine entity or merely an aggregate of regressed individuals? Bion insists it is not reducible to its members, yet paradoxically locates its apparent substantiality in a collective regression that dissolves individual distinctiveness—a position that simultaneously affirms and problematizes group reality. Simondon offers a contrasting ontogenetic answer: the group is a syncrystallization, contemporaneous with its own genesis, neither the sum of pre-formed personalities nor their container. Second, the clinical-structural question: how does the group function as a therapeutic medium? Yalom’s systematic taxonomy of therapeutic factors—cohesiveness, universality, interpersonal learning—treats the group as a social microcosm whose curative power resides in its reproduction of primary relational patterns. Flores, writing from the addiction field, stresses the group’s holding and confrontational functions, its capacity to break denial through shared norm-formation. Third, the dynamic question: what covert forces operate beneath the work surface? Bion’s basic assumption theory—dependency, fight-flight, pairing—remains the master framework for understanding how primitive mental states colonize any assembled collectivity. Across these axes, leadership, regression, resistance, and cohesion emerge as the recurrent analytic pressure-points.