This study investigated the effects of internal and demographic variables on civic development in late adolescence using the construct civic purpose. We conducted surveys on civic engagement with 480 high school seniors, and surveyed them again two years later. Using multivariate regression and linear mixed models, we tested the main effects of civic purpose dimensions (beyond-the-self motivation, future civic intention), ethnicity, and education on civic development from Time 1 to Time 2. Results showed that while there is an overall decrease in civic engagement in the transition out of high school, both internal and social factors protected participants from steep civic decline. Interaction effects varied. Ethnicity and education interacted in different ways with the dimensions of civic purpose to predict change in traditional and expressive political engagement, and community service engagement.