Although some questions remain regarding the efficacy of adventure therapy, existing research suggests that it is an effective modality for treatment. For example, a meta-analytic review of 197 studies of adventure therapy participant outcomes (2,908 effect sizes, 206 unique samples) found that the short-term effect size for adventure therapy was moderate ("Hedges' g" = .47) and larger than for alternative (.14) and no treatment (.08) comparison groups. There was little change during the lead-up (.09) and follow-up periods (.03) for adventure therapy, indicating long-term maintenance of the short-term gains.