We examined trajectories of ethnic identity exploration, resolution, and affirmation and their associations with depressive symptoms and self-esteem 3.5 years later among early and middle adolescent Mexican-origin girls (N = 338). Findings indicated that exploration, resolution, and affirmation increased over time for both cohorts. Among early adolescents, growth in exploration was associated with more depressive symptoms during middle adolescence, whereas higher initial levels and greater rates of change of affirmation predicted fewer subsequent depressive symptoms. Among middle adolescents, higher baseline levels of exploration and affirmation predicted fewer depressive symptoms in late adolescence. Higher initial levels and greater change in affirmation predicted higher self-esteem among both cohorts. Findings highlight the developmental and multifaceted quality of ethnic identity and that associations between ethnic identity and adjustment may vary by adolescent developmental stage.