This study sought to determine the self-concept level, expectancy of success in school subjects, and actual achievement in those subjects of disadvantaged youths in high school in comparison to advantaged boys. The subjects (Ss) consisted of 100 disadvantaged and 100 advantaged boys from an urban integrated high school. No Ss were in the college preparatory curriculum. The level of aspiration was determined by requesting Ss to set down the grades they thought they would get at the end of the semester in two courses, English and science. Then, the actual achievement was obtained at the end of the semester. Self-concept was measured with a standard semantic differential instrument. Disadvantaged youths, in comparison to advantaged males, showed higher course-grade predictions, more positive self-concepts, and lower achievement. It may well be that disadvantaged boys, due in part to an inconsistent pattern of past achievement and lower achievement motivation, are less realistic and more variable than advantaged boys about future achievement levels. (Author/JM)