Regulatory Focus Theory's two fundamental processing orientations, Prevention Focus and Promotion Focus, have been shown to capture important differences in problem-solving motivation, goal pursuit, and individual-task ‘fit’, although some ambiguity remains regarding the nature of these differences; they have been construed as chronic but have also been related to specific situational factors. Separately, understandings of temperament (hereditable, physiological-based individual differences) have advanced significantly, although efforts to validate measures of temperament have been frustrating. Reinforcement Sensitivity Theory posits two fundamental temperaments, the Behavioral Inhibition System (an avoidance system sensitive to punishments and threats) and the Behavioral Activation System (an appetitive/approach system sensitive to rewards). We relate Regulatory Focus Theory to Reinforcement Sensitivity Theory, initiating the integration of Promotion Focus and Prevention Focus with the extensive extant theory and nomological networks of temperament and highlighting conspicuous empirical divergence between the two systems.