Parents' racial socialization messages, including messages focused on awareness, preparation, and strategies for managing racial discrimination, are necessary to help African American youth successfully navigate their daily lives. However, mixed findings regarding the utility of preparation for bias messages for African American youth's mental health adjustment raise questions about the conditions under which these protective racial socialization messages are most beneficial to African American youth. The current study examined the degree to which communication and trust as well as anger and alienation in the mother-adolescent relationship moderated associations between 2 types of preparation for bias messages, cultural alertness to discrimination and cultural coping with antagonism, and adolescent mental health. Participants were 106 African American adolescents (57% female; mean age = 15.41) who reported about their receipt of racial socialization messages, mother-adolescent relationship quality, and depressive symptoms. Hierarchical regression analyses indicated that positive associations between cultural alertness to racial discrimination and youth depressive symptoms were weaker for boys in the context of higher mother-adolescent communication and trust; communication and trust were not similarly protective for girls. For boys, the positive associations between cultural coping with antagonism messages and depressive symptoms were stronger in the context of high anger and alienation in the mother-adolescent relationship. Findings suggest that qualities of the mother-adolescent relationship, in which preparation for bias messages are delivered, are important for understanding the mental health adjustment of African American adolescents.