This meta-analysis synthesized the available empirical evidence on the impact of interventions on the development and enhancement of mathematical word problem solving skills for K-12 students with learning disabilities (LD) and those with mathematics difficulties (MD). A total of 33 studies met inclusion criteria for this meta-analysis. After removing 2 influential data points, 31 true-experimental or quasi-experimental studies (34 independent effect sizes) contributed effect sizes for this meta-analysis. Results of a random effects model showed that word problem solving interventions yielded a moderate positive mean effect size (g = 0.56, 95% confidence interval [0.40, 0.72]). The relation between word problem solving interventions and student learning was moderated by grade level, year of publication, type of measure, intervention model type, and implementer. On average, intervention effects were larger for (a) elementary grades than secondary grades, (b) studies published between 2000 and 2009, (c) researcher-developed than norm-referenced measures, (d) researcher implementers than teacher implementers. Results also showed intervention effects for schema-based transfer instruction were larger than those for schema-based instruction, strategy instruction, and other. These results support mathematics word problem solving interventions for students with LD and/or MD. We conclude by discussing directions for future research and implications for practice.