In this paper, we study the determinants of university dropouts with a longitudinal data set on students' enrollments at the University of Montreal. With a bivariate probit model with selectivity bias, the variables explaining persistence and dropouts are related to the information gathered on the student about his or her interests and abilities. The average number of students in first-year compulsory courses is also a determining factor. These results support a simple version of Manski's model of schooling as an experimentation process and the models of sequential decisions of Altonji, Oosterbeek and Hartog et al. Also supported is the idea of person-environment fit, pioneered by Tinto.