A meta-analysis of play therapy outcomes with children was conducted to determine the overall effectiveness of play therapy and the variables related to effectiveness. Hierarchical linear modelling was used to analyse the data. The analysis showed an average treatment effect of 0.66 standard deviations. A strong relationship between treatment effectiveness and the inclusion of parents in the therapeutic process was reported. The duration of therapy also appeared to be related to treatment outcomes, with maximum effect sizes occurring after approximately 30 treatment sessions. Play therapy appeared to be as effective as non-play therapies in treating children experiencing emotional difŽ culties. Recommendations for future researchers focus on explaining therapeutic or participant characteristics that are related to treatment effectiveness