To examine the association between the frequency of family dinners and positive and negative dimensions of mental health in adolescents and to determine whether this association is explained by the quality of communication between adolescents and parents. A community sample of 26,069 adolescents (aged 11 to 15 years) participated in the 2010 Canadian Health Behaviour of School-aged Children study. Adolescents gave self-report data on the weekly frequency of family dinners, ease of parent-adolescent communication, and five dimensions of mental health (internalizing and externalizing problems, emotional well-being, prosocial behavior, and life satisfaction). Regression analyses tested relations between family dinners, parent-adolescent communication, and mental health. The frequency of family dinners negatively related to internalizing and externalizing symptoms and positively related to emotional well-being, prosocial behavior, and life satisfaction. These associations did not interact with differences in gender, grade level, or family affluence. However, hierarchical regression analyses found that these associations were partially mediated by differences in parent-adolescent communication, which explained 13% to 30% of the effect of family dinners on mental health, depending on the outcome. These findings, though correlational, revealed a dose-response association between the frequency of family dinners and positive and negative dimensions of adolescent mental health. The ease of communication between parents and adolescents accounted for some of this association.