The meta-analysis addressed three research questions: (1) What is the causal effect of teacher coaching programs on classroom instruction and student achievement?; (2) Are specific coaching program design elements associated with larger effects?; and (3) Do changes in teacher practice from coaching programs translate into improvements in student achievement? Results found large positive effects of coaching on teachers' instructional practices. In addition, teacher coaching had an independent, positive effect on student achievement, as indicated by performance on standardized tests. Pairing coaching with group training was found to be associated with a larger effect on instruction and on achievement. There was no clear evidence that more hours of coaching were associated with larger impacts, suggesting that the quality and focus of the coaching may be more important than the actual number of contact hours. [This article is a research review of: Kraft, M., Blazar, D., & Hogan, D. (2018, August). "The effect of teacher coaching on instruction and achievement: A meta-analysis of the causal evidence." "Review of Educational Research," 88(4), 547-588 (see EJ1185488).]