We propose a motivational affordance account to explain both stability and variability in risk-taking propensity in major decision domains. We draw on regulatory focus theory to differentiate two types of motivation (prevention, promotion) that play a key role in predicting risk-taking. Study 1 demonstrated that prevention motivation is negatively associated with risk-taking across six key decision domains, including health/safety, ethics, recreation, gambling, investment, and social. In contrast, promotion motivation is positively associated with risk-taking in the social and investment domains. Study 2 replicated the same pattern and provided direct evidence that promotion motivation is a strong predictor of risk-taking only in domains where there is true potential for gains. Study 3 manipulated promotion (vs. prevention) motivation experimentally to demonstrate that motivational affordance is a critical mechanism for understanding risk-taking behaviors.