Although disinhibition is widely implicated in impulse-control-related psychopathologies, debate remains regarding the underlying approach and avoidance processes of this construct. In two studies, we simultaneously tested three competing models in which varying levels of extraversion, neuroticism, and hemispheric lateral preference are associated with disinhibition. In both studies (Study 1, N = 92; Study 2, N = 124), undergraduate students were randomly allocated to one of two versions of the go/no-go task: one where participants were primed through reward to make more “go” responses and another where no such priming occurred. Neuroticism, extraversion, and hemispheric lateral preference measures were also collected. Across both studies, disinhibition was greatest in individuals who reported both a left hemispheric lateral preference and high neuroticism. This pattern was only found for those who were primed through reward to make more “go” responses. There was no association with extraversion. Contrary to previous research, our results suggest that left hemispheric asymmetry and neuroticism and not extraversion drive disinhibited approach, following the establishment of a prepotent approach response set. This has salient implications for the theoretical understanding of disinhibited behavior, as well as for the study of continued maladaptive approach behavior.