This thesis is an investigation of the moderating effect of identity decision-making styles on the relation between adolescent problem behavior and psychosocial well-being. Participants included 1857 adolescents ages 16 and 17 who completed the Youth Self-Report Questionnaire in Cycle 4 of the National Longitudinal Survey of Children and Youth. It was hypothesized that the negative relation between problem behavior involvement and psychosocial well-being would be stronger for individuals classified as having a predominantly diffuse-avoidant identity processing style than for normative or informational participants, and that this relation would be stronger in the normative group than in the informational group. All hypotheses were supported in a structural equation model linking problem behavior and well-being.