This article provides a synthesis of word-problem-solving intervention research with samples of students with learning problems (i.e., mild disabilities and at risk for mathematics failure). The effectiveness of word-problem-solving instruction in 25 outcome studies was examined across student characteristics (e.g., grade, IQ); instructional features (e.g., intervention approach, treatment length); methodological features; skill maintenance; and generalization components. Separate analyses were performed for group-design studies and single-subject studies using standardized mean change and percentage of nonoverlapping data (PND), respectively. The overall mean weighted effect size (d) and PND for word-problem-solving instruction were positive across the group-design studies (ES = +.89) and single-subject studies (PND = 89%). In addition, positive effects for skill maintenance and generalization were found for group design (ES = +.78 and +.84, respectively) and single-subject studies (PND = 100%). Computer-assisted instruction was found to be most effective for group-design studies. Effects for representation techniques and strategy training were found to be significantly higher than the "other" approach for both group-design and single-subject studies. Long-term (> 1 month) intervention effects were significantly higher than short- or intermediate-term interventions for group-design studies, whereas both long-term and intermediate treatments were seen to be more effective than short-term treatments for single-subject studies. Other significant effects found for group-design studies only in terms of student characteristics, instructional features, and methodological features are reported. Finally, implications of the current analysis for future research in the area of word-problem solving are discussed.