Human capital theorists suggest that education is a form of investment in the individual's future which yields economic dividends commensurate to the investment. Another school of thought criticizes this theory for not showing the relationship between schooling, productivity, and earnings, and holds that for minority workers, program completion may be more important than the number of years spent in a program. A review of the literature on minority income distribution shows that blacks earn less than whites and women less than men; that education, sex, and age influence posttraining earnings mainly through occupational choice and literacy; and that social welfare status influences earning through occupational choice and time in program. A New York City study conducted to evaluate the effects of education on posttraining wages among participants in a large manpower program finds that: (1) When marginality factors--conditions which may result in underutilization of a particular group of workers, such as physical or mental disabilities, discriminatory practices, characteristics of some occupations, or lack of skills or training--are at work, literacy has no effect on wages; (2) when faced with limited occupational opportunities, individuals with higher social welfare status tend to prefer lower status trades which require less training time; (3) educational marginality neutralizes all other variables in posttraining earnings, and, under conditions of marginal education, neither literacy nor occupation contributes significantly to the determination of wages; and (4) employers reward the possession of a diploma more than the number of years in training. (AOS)