Aggregate college data are used to help understand how college characteristics influence the decision for freshman to remain in school another year. Taking advantage of the aggregate data, we estimate a three-stage least squares model which takes retention, enrollment and SAT scores as all endogenous. Our results highlight interactions between the three endogenous variables which confirms our suspicion of the need for multiple equations. In addition, a variety of specific results emerge, including the impact of interviews, ability, socioeconomic status, and the student-faculty ratio of the college. In general many of these results can be understood in terms of the human capital model in which the decision to continue depends on a weighing of the benefits against the full costs of college. Both this framework and our specific estimation bring new evidence to an examination of the retention decision.