This study examined the quality of teacher-child interactions and exposure to mathematics instruction as predictors of 5th grade student's mathematics achievement. The sample was a subset of the children involved in the NICHD-SECC longitudinal study (N = 657). Results indicate that, even after controlling for student demographic characteristics, more exposure to mathematics instruction was related to increased fifth grade mathematics achievement for both calculations and applied problems assessments, but there was no main effect for improved instructional quality. Findings also indicate that, in classrooms where lower instructional quality was observed, greater exposure to mathematics instruction predicted improved mathematics achievement. Findings are discussed in terms of differing aspects of mathematics instruction and the possible compensatory role of exposure to instruction in classrooms of lower quality.