The purpose of the study was to meta-synthesize research findings on the effectiveness of problem posing and to investigate the factors that might affect the incorporation of problem posing in the teaching and learning of mathematics. The eligibility criteria for inclusion of literature in the meta-analysis was: published between 1989 and 2011, reported problem posing as an intervention, employed experimental research design, and provided data necessary to compute effect sizes. The large positive effect sizes (Hedges' g) showed that problem posing activities provide considerable benefits for: mathematics achievement, problem solving skills, levels of problems posed, and attitudes toward mathematics. Several noteworthy "limitations" of this "study" were discussed.