The purpose of this meta-analytic review was to investigate the relation between motivation and reading achievement among students in kindergarten through 12th grade. A comprehensive search of peer-reviewed published research resulted in 132 articles with 185 independent samples and 1,154 reported effect sizes (Pearson's r). Results of our random-effects metaregression model indicate a significant, moderate relation between motivation and reading, r = 0.22, p < 0.001. Moderation analyses revealed that the motivation construct being measured influenced the relation between motivation and reading. There were no other significant moderating or interaction effects related to reading domain, sample type, or grade level. Evidence to support the bidirectional nature of the relation between motivation and reading was provided through longitudinal analyses, with findings suggesting that earlier reading is a stronger predictor of later motivation than motivation is of reading. Taken together, the findings from this meta-analysis provide a better understanding of how motivational processes relate to reading performance, which has important implications for developing effective instructional practices and fostering students' active engagement in reading. Theoretical and practical implications of these findings for reading development are discussed.