The study assessed the effects of the quality of reading and math instruction and classroom climate on the academic skills and engagement of 314 children in 245 classrooms at the end of third grade. All of the children in the study were from families with low incomes. On a classroom observation measure developed for the study, regression analyses revealed that relatively high ratings on the reading and math instruction subscales, which were scored after a half-day observation, predicted better reading and math achievement test scores, respectively, for third graders who had previously had poor academic performance, but did not have a significant effect for relatively high-performing students. High teacher ratings on the reading instruction and classroom climate observation scales predicted high levels of student engagement. The findings suggest the importance of high-quality teaching for economically disadvantaged children who have poor academic skills.