Drawing from the literature on the interpersonal functions of self-control, we examined longitudinal associations between trait self-control and social desirability, using a survey of the general population in the Netherlands. Trait self-control at baseline was positively associated with social desirability at a follow-up, even when controlling for prior levels of social desirability. That is, high self-control contributed to individuals' tendency to give socially desirable responses in self-reports. This effect was moderated by individual differences in agreeableness. Highly agreeable individuals were more likely to “use” their self-regulatory resources to respond in a socially desirable manner, compared to less agreeable individuals, suggesting that individuals might use self-regulatory resources in a way consistent with the motivational bases of their personality.