In this fourth report of the Impact Study, a formal research project designed to describe the effects of changing patterns of institutional and student financing on postsecondary enrollments, some of the findings of two surveys of freshman students are compared. The two surveys were performed in 1972 and 1977, and although they drew samples differently, their responses' frequency distributions may be compared with some degree of validity. Focus is on the changes in patterns of socioeconomic, personal, academic, and family characteristics of students enrolled at a variety of postsecondary institutions: four-year public colleges, four-year private colleges, two-year public (regional) colleges, two-year private colleges, and vocational-technical institutions. Data are included on expected and actual parental contributions to student expenditures, mean amounts of various types of student aid, reasons for college choice, racial or ethnic group membership distribution, family income, students' fathers' educational level, students' types of high school programs and grades, degree aspirations, marital and residence status, and freshman educational costs. (MSE)