Many Black young adults engage in their communities through critical action, or activism, as they transition into adulthood. However, knowledge about predictors of critical action remain sparse. The present longitudinal study addresses this gap by exploring links between critical action, ethnic-racial identity, and racial discrimination among 143 Black youth who were surveyed as adolescents (M[subscript age] = 15; 66% female) and again as young adults (M[subscript age] = 20). Using hierarchical logistic regression, we found that young adult experiences of racial discrimination were related to increased odds of critical action, accounting for adolescent racial discrimination, gender, caregiver education, and postsecondary enrollment. We also found that criminalizing discriminatory experiences (e.g., being stopped by the police) during young adulthood were related to increased odds of critical action. Our findings document changes in racial discrimination and ethnic-racial identity during the transition to adulthood and suggest that some marginalized youth may transform adverse experiences into critical action.