The purpose of this meta-analysis was to examine the effects of writing intervention on students' mathematical attainment based on their achievement (mathematics standardized test scores) and their attitudes toward mathematics (mathematical motivation and interest). Twelve studies with 19 effect sizes were selected for inclusion in the present meta-analysis. Results indicated that the overall effect size equalled 0.42. The small sample size (12 studies) in the present meta-analysis limits the generalizations that might be made regarding the overall impact of writing intervention on students' mathematical attainment. However, the implication from the present study is that integrating writing into mathematics classrooms can be a useful instructional strategy to increase students' mathematics success.