Using structural equation modeling and cross-lagged analyses, this longitudinal study investigates ethnic identification, a group-based coping strategy, as a mediator of the influence of perceived discrimination on psychological well-being and willingness to engage in activism on behalf of one’s ethnic group among Latino students in both their first and fourth years of college. We found cross-sectional evidence for the rejection–identification model (RIM) during both years of college. Further, multiple step bootstrapping analyses of the longitudinal data showed that the relationships between perceived discrimination during Year 1 and both well-being and activism during Year 4 were sequentially mediated by activism during Year 1 predicting ethnic identification during Year 4. These data extend the RIM by including activism as an additional outcome variable that has important implications for Latino students across time.