Enrollment trends between 1965 and 1978 at state colleges and universities belonging to the American Association of State Colleges and Universities are analyzed in connection with major events that either raised or lowered the cost of attending these institutions. Headcount data, full-time and part-time enrollments, enrollment of female students, and enrollment of graduate and undergraduate students were assessed. The following factors influencing enrollments were assessed: unemployment among 18-to-24-year-olds, urban and rural location, tuition, room and board, expiration of veteran's benefits, rejection of Basic Educational Opportunity Grant applicants, and the growth in student aid. Based on the analysis, the aptness of several popular enrollment theories are evaluated. It is concluded that enrollments in state colleges and universities seem acutely sensitive to the ability of students to pay the costs of college attendance. Institutional planning has become more complicated and outcomes for the 1980s will depend on assessment of economic and political changes that affect higher education. (SW)