Objective. The purpose of this study was to find whether existing studies of treatment using sensory integration approaches support the efficacy of these approaches.

Method. With meta-analysis, the results of sensory integration efficacy research studies published from 1972 to the present were synthesized and analyzed. Sixteen studies were used to compare sensory integration effect with no treatment (SI/NT), and 16 were used to compare sensory integration effect with alternative treatments (SI/ALT). Overall average effect sizes, comparisons of the effect sizes for different dependent variables, and secondary factors associated with effect size variation were examined.

Results. The weighted average effect size of SI/NT studies was .29. However, there was a significant difference between the average effect sizes of the earlier studies (.60) and the more recent studies (.03). Of the outcome measures, larger effect sizes were found in the psychoeducational category (.39) and motor category (.40). Of SI/ALT studies, the average effect size was .09, not significantly different from zero.

Conclusion. Three central conclusions can be made. First, in the SI/NT comparison, a significant effect was replicated for sensory integration treatment effects in earlier studies, but more recent studies did not show overall positive effects. Second, larger effect sizes were found in psychoeducational and motor categories. Third, sensory integration treatment methods were found to be as effective as various alternative treatment methods.