Abstract Two studies investigated the utility of the Self-Regulation Model of Decision Making (SRMDM) for explaining and predicting adolescents' decision making in social situations. Participants were mostly ninth and eleventh graders, with a first study consisting of all boys and a second similar study composed of boys and girls. Measures included a new assessment of decision-making skill (the Decision-Making-Competency Inventory or DMCI), the Weinberger Adjustment Inventory (WAI), an importance assessment of social–relational goals, and peer ratings of social behavior. Results across both studies showed that adolescents' valuing of social–relational goals and their decision-making competency were typically the best predictors of their social behaviors. The results also showed that adolescent girls — especially the older ones — were the most affirming of socially competent behavior whereas older adolescent boys tended to be the least affirming of this. Older adolescent girls also scored highest on the DMCI, which was found to have adequate psychometric properties.