Neighborhood social processes may have important implications for parenting processes and ethnic-racial identity (ERI) processes and content in adolescence. Past research suggests that adolescents whose parents engaged in more cultural socialization, an important aspect of parental racial socialization, had higher levels of ERI processes and content. Parenting, however, is also situated within neighborhood contexts and can be influenced by resources available in neighborhoods. For example, having neighbors who share mutual values, trust one another, and appreciate/celebrate one's heritage culture may be a resource that promotes parents' efforts to engage in cultural socialization. We prospectively examined (from [x-bar][subscript age] = 10.9-15.8 years) a model in which U.S. Mexican parents' perceptions of neighborhood social and cultural cohesion supported parents' engagement in higher levels of cultural socialization and in turn promoted adolescents' ethnic-racial identity processes and content. We tested a longitudinal mediation model with a sample of 749 U.S. Mexican adolescents (30% Mexico born; 48.9% female) and their parents. Mother-adolescent models suggest mothers' perception of neighborhood social and cultural cohesion in late childhood promoted middle adolescents' ERI affirmation via intermediate increases in maternal cultural socialization. Similar patterns were observed for ERI resolution, but only for adolescents whose mothers were born in the United States. We did not find evidence for mediation in the father-adolescent models. Findings are discussed in the context of the promoting nature of socially and culturally supportive neighborhood environments for U.S. Mexican families and adolescents.