The authors explored the moderating effect of teachers' expectancies and general sense of efficacy on the relationship between students' achievement and their cognitive engagement and achievement 1 year later. They used hierarchical linear modeling with a longitudinal sample of 79 mathematics teachers and their 1,364 secondary school students coming from 33 schools serving disadvantaged communities in Quebec (Canada). Results indicate that teachers' self-reported beliefs directly influenced student academic experience. However, they did not influence more importantly low-achieving than high-achieving students. Such findings suggest that in schools serving low socioeconomic status students, teachers should be made aware of the role their attitudes can play on students' cognitive engagement and achievement. Special efforts should also be made to help them develop positive attitudes toward all students. (Contains 3 tables.)