To develop and test a theoretical model, based on the Theory of Reasoned Action (Fishbein and Ajzen, 1975), for understanding and predicting the decision to stay in or drop out of school, to identify the specific beliefs that are the basis of that decision, and to evaluate the use of moderator variables (sex, race) to individualize the model, 1,732 tenth grade students completed a questionnaire. The students represented 10 high schools from five school districts. The questionnaire was developed as the result of 250 interviews with high school students. An analysis of the data from 712 subjects (356 persisters, 356 potential dropouts) showed the feasibility of applying the Theory of Reasoned Action to the dropout problem. Social influences and attitudes were found to be the two immediate determinants of a student's intentions. Students' decisions were determined more by their own attitudes toward dropping out or staying in school than by their perceptions of what other people wanted them to do. These attitudes were based on the students' beliefs about the consequences of their behavior. Generally, the student who was likely to stay in school perceived immediate social benefits and societal rewards for his actions, while the potential dropout had negative feelings about unavoidable school experiences and was less likely to perceive any good reasons for staying in school. The use of moderator variables (sex, race) improved the validity and usefulness of the model. The findings suggest that effective intervention programs must seek to change beliefs in order to change behaviors. (BL)