Purpose. The social gradient in adolescent mental health is well established: adolescents’ socioeconomic status (SES) is negatively associated with their mental health. However, de-spite changes in social cognition during adolescence, and theory and evidence that SES, so-cial cognitions, and adolescent mental health are associated, little is known about whether social cognitions mediate this gradient. Methods. This study used three data waves, each six months apart, from a socioeconomi-cally diverse sample of 1,429 adolescents (Mage = 17.9) in the Netherlands. With a longitu-dinal mediation model, we examined whether three social cognitions (self-esteem, sense of control, and optimism) mediated the associations between perceived family wealth and four indicators of adolescent mental health problems (emotional symptoms, conduct prob-lems, hyperactivity, and peer problems). Results. Adolescents with lower perceived family wealth reported more emotional symp-toms and peer problems concurrently and an increase in peer problems six months later. Adolescents with lower perceived family wealth reported a decrease in sense of control six months later, and lower sense of control predicted increases in emotional symptoms and hyperactivity six months later (though not in the multivariate model with all three social cognitions). Perceived family wealth predicted neither later self-esteem nor optimism, though we found concurrent positive associations between perceived family wealth and all three social cognitions, and concurrent negative associations between social cognitions and mental health problems. Conclusion. Our findings indicate that social cognitions may be an overlooked mediator of the social gradient in adolescent mental health. Future research on this social gradient may benefit from incorporating a focus on social cognition
