Recent research has demonstrated that decision-making competence (DMC), a latent construct reflecting individual differences in rational thought, is predictive of real-world decision outcomes at various stages of life. This construct has been shown to be associated with concurrent and retrospective accounts of health-risking behavior, but its predictive validity has yet to be demonstrated. In the present study, we examine this issue using a 2-year prospective, multiple-informant design. Specifically, we tested the degree to which preadolescent DMC (PA-DMC) obtained at ages 10-11 years (Time 1; N = 101) predicted both self-reports and caregiver reports of emotional, behavioral, and peer-related difficulties obtained 2 years later (Time 2; N = 76). Holding variables such as numeracy and inhibitory control constant, lower Time 1 PA-DMC scores predicted greater reported Time 2 psychosocial difficulties (i.e. peer, conduct, emotional, and hyperactivity/inattention problems). Additionally, higher PA-DMC scores were associated with greater self-reported prosocial behaviors at Time 2. These results highlight the utility of testing individual differences in rational responding. We discuss the potential for improving children’s decision-making processes.