This study uses data from the 1989-1994 Beginning Postsecondary Survey to ascertain the prevalence of such nontraditional enrollment practices as part-time and stop-out behavior. The decision to enroll initially as a part-time or full-time student was examined, contingent on the initial decision to attend college. A theoretical model that explicitly recognizes the role of employment opportunities in determining full-time/part-time enrollment options is developed. Empirical results from a logit model of the initial enrollment decision are consistent with this theoretical model and indicate that economic factors such as expected earnings and the unemployment rate significantly influence the decision to enroll on a part-time versus a full-time basis. (Contains 5 tables and 39 references.) (Author/SLD)