A causal model was developed to study teacher, student, and educational expectations. The substantive issue concerns the impact of teachers' expectations on students' expectations. The subjects, 6,032 high school students, were drawn from a major Canadian city in 1959. Variables include social origins, intellectual ability, program, academic achievement, teachers' expectations, and educational ambition. The model, a system of cause-effect relationships, is presented in block-recursive form. That is, the relationships among the blocks are recursive but reciprocal causation is possible within blocks. The parameters of the model were estimated via path analyses, a generalization of multiple regression to systems of causally related variables. Results of this study include three major findings: a) Students affect teachers much more than they are affected by the expectations teachers hold. b) The effect of teachers' expectations on student is negative. c) In general, teachers' expectations are irrelevant for girls, with the exception of the fourth year of high school, while, for boys, an early influence from students to teachers increase from year to year and the effects of teachers' expectations increased dramatically in the fourth year. A 51-item bibliography, tables, and figures are included. (MJM)