This paper explores the structure of groups and gangs and looks at the states of mind of the individuals within these different constellations from a descriptive and theoretical point of view. The terms ‘group’ and ‘gang’ are defined in specific ways as related to Klein's description of the depressive position, on the one hand, and the paranoid-schizoid position, on the other. The elaboration of these concepts by post-Kleinian writers, particularly Rosenfeld, is also examined. Drawing on examples from society, Philip Larkin's poem Aubade, William Golding's novel Lord of the Flies and clinical work with groups of children, the paper considers how and why ‘grouping’ and ‘ganging’ occur and what factors determine a move from one state of mind to another.