An influential theory within personality neuroscience suggests that trait extraversion is underpinned by individual differences in dopamine function. In a review of the relevant literature, we evaluate this theory in light of the evidence from molecular genetics, neuroimaging, and psychopharmacology. Evidence linking individual differences in extraversion with dopamine-relevant genes, structural volume of dopamine-rich brain regions (e.g., in striatal and ventral prefrontal areas), dopamine receptor availability, and frontal alpha asymmetry is mixed at best. Evidence concerning both scalp recorded ( electroencephalogram) and hemodynamic (functional magnetic resonance imaging) neural responses to rewards appears somewhat more promising. Perhaps the best evidence concerns extraversiondependent responses - both neural and behavioural - to dopaminergic drugs. Future research in this area must go beyond the demonstration of theoretically consistent associations and attempt to provide more specific causal evidence for the dopamine hypothesis of extraversion. A further challenge is to expand this hypothesis to incorporate other neurobiological processes that are likely to underlie this trait.