Research-based instruction is necessary to support students' reading development, and professional development (PD) is a critical avenue to ensuring high-quality instructional practices. To date, there has been no comprehensive review focused on the effects of teacher PD on student reading achievement. As such, the purpose of the present meta-analysis was to examine the impact of teacher PD on reading outcomes for students in kindergarten through 8th grade. A secondary aim was to determine whether study, program, or participant characteristics were potential moderators of these effects. A comprehensive search of published and unpublished research between 1975 and 2017 resulted in 28 studies that met prescribed criteria. Results indicate that teacher PD has a moderate and significant, positive average effect on reading achievement. However, moderator analyses did not explain the variance in the effects of PD on student outcomes. Primarily, studies represented typically-developing students in the elementary grades, with only three studies including middle school students and four studies including reading outcomes of students with or at-risk for reading disabilities. Recommendations for improved study designs that allow for more in-depth investigation of the characteristics of effective PD and mechanisms of change in student outcomes are discussed.