Examined the relation of psychosocial and behavioral conventionality-unconventionality to health-related behavior in cross-sectional data from 1,588 male and female 7th to 12th graders. Conventionality-unconventionality was represented by personality, perceived social environment, and behavior variables selected from the social-psychological framework of problem-behavior theory (R. Jessor & S. L. Jessor, 1977). Greater psychosocial conventionality correlates with more regular involvement in health-related behavior (regular physical activity, adequate sleep, safety belt use, attention to healthy diet). Greater behavioral conventionality (less involvement in problem behaviors such as marijuana use, problem drinking, delinquent-type behavior, and greater involvement in conventional behaviors such as church attendance) was also associated with greater involvement in health-maintaining behavior. The overall findings provide support for the extension of problem-behavior theory to the domain of adolescent health behavior and for the relevance of the dimension of conventionality-unconventionality.