The role of teacher, family and the background of students in conducting homework and math performance were investigated. Participants were 7,725 Spanish adolescents with the mean age of 13.78 (± .82) and 2,246 teachers who taught the above mentioned students. A two-level hierarchical linear analysis, students (N = 7,541) and classrooms (N = 353), was performed, adjusted for background and prior ... [Show full abstract] achievement variables. The results indicate that the autonomous work of the students is more important than the time they spent on homework. The weight that homework has in school grades (Level 1) and frequency allocation (level 2) are the two most important variables related to the policy of the teacher assignments. Finally, family involvement in learning and the importance of homework for the family also appear positively and significantly linked to the performance.