Early work by Lex Cools suggested that the caudate nucleus (dorsal striatum) plays a role in programming social behaviour: enhanced activity in the caudate nucleus increased the extent to which ongoing behaviour is controlled by the individual's own behaviour (internal control) rather than by that of its partners (external control). Interestingly, later studies by others have indicated that the ventral striatum plays a role in external rather than internal control. Here, I discuss the role of these different striatal areas - and the emotional (ventral striatum) and cognitive control (dorsal striatum) system in which they are embedded - in the organization of social behaviour in the context of locus of control. Following on from this discussion, I will pay particular attention to individual differences in social behaviour (individuals with more internal or external control), focusing on the role of dopamine, serotonin and the effects of stress-related challenges in relation to their different position in a dominance hierarchy. I will subsequently allude to potential psychological and behavioural problems in the social domain following on from these differences in locus of control ['social obliviousness' (dorsal stratum) and 'social impulsivity' (ventral striatum)]. In doing so, I provide as a tribute a historical account of the early research by Lex Cools.