Although diversity has been considered a vital component in higher education over the past several decades, little research—theoretical or empirical—has rigorously examined the determinants of minority enrollments in higher education. By drawing on literature across several fields, this article helps close this gap by testing competing theoretical explanations for minority enrollments in American public colleges and universities. We examine African-American and Latino freshman enrollments for over 500 public institutions from 1992 to 2000. Our results support claims made by university administrators regarding the importance of economic and environmental constraints on diversifying college campuses. We also find, however, that political, bureaucratic, and structural factors are also important determinants of diversity. These findings highlight the significance of contextual variables in determining policy outcomes.