This study was designed to provide an overall estimate of proprietary schools' contribution to the equality of educational opportunity in the postsecondary educational system. Two compatible databases, the National Longitudinal Study of the High School Class of 1972 (NLS) and High School and Beyond (HSB), were used to draw two parallel proprietary samples. Each proprietary sample was compared with its counterparts in the community college and the four-year institution sectors. Gender, race, socioeconomic status, aptitude, and Students' and their mothers' educational aspiration were the factors tested in the study to determine the extent to which they contribute to students' choice of proprietary schools and their educational attainment in a given period of time. Discriminant analysis was utilized to differentiate the characteristics of proprietary school enrollees from the characteristics of those who entered community colleges and four-year institutions. Multiple regression was conducted on each group of students to identify the major factors associated with students' educational attainment by the type of institution of first enrollment. The major findings of this study include: (1) Proprietary schools enrolled a considerable number of "disadvantaged" students: women, minorities, people from low socioeconomic background, and those with low aptitude scores. (2) Students’ and their mothers’ educational aspirations were the most influential factors affecting students’ choice among the three types of postsecondary institutions, and proprietary students’ aspirations were lower than that of community college and four-year institution students. (3) Most proprietary Students did not reach the level of a two-year degree or beyond, and those who eventually attained a two-year degree or beyond were very likely to be students with high aptitude. (4) Study of the delayed entrants into proprietary schools confirmed the major findings derived from the initial entrants, except the aspiration variable played a less significant role in determining the educational attainment of delayed entrants than that for the initial entrants. / Ed. D.