Mattering is the tendency to view the self as significant to other people. Theoretically, mattering has been proposed to promote psychosocial well-being. Although prior research has found positive associations between mattering to parents and psychosocial well-being among adolescents, extant studies have not clarified whether perceptions of mattering predict psychosocial well-being or the other way around. Thus, the direction of the association needs verification. The purpose of this study was to examine the direction of associations between adolescents' mattering to parents and friends and adolescents' depressive symptoms and problem behaviors using cross-lag models. A two-wave annual survey assessed mattering to family and friends, depressive symptoms, and problem behaviors of students in grades 6 to 9 (N = 164; 56.1% girls) in a school district in western Canada (Time 1 age range = 11 to 15 years; mean age = 12.23; standard deviation = 1.07). Structural equation modeling was used to assess concurrent, auto-regressive, and cross-lagged associations between mattering and psychosocial well-being. Mattering to mother, father, and friends was assessed in separate models. Significant lags were found only between mattering to friends and depressive symptoms and problem behaviors, with positive associations suggesting a form of socialization through mattering. With one exception, mattering to parents was not directly associated with psychosocial well-being over time. However, gender moderated the association between mattering to mother (Time 1), depressive symptoms (Time 2), problem behaviors (Time 1), and mattering to mother (Time 2). Taken together, these results suggest that mattering may not be as strongly protective of adolescent well-being as previously suggested.