Background: Persons with intellectual disabilities (ID) often show challenging behaviour. We review distinct interventions that are applied to treat these challenging behaviours, and analyse intervention effects and moderating variables. Method: A literature search was conducted using the databases ERIC, PsycINFO, Web of Science and Medline. A random-effects meta-analysis was carried out, supplemented with sensitivity, subgroup, meta-regression, and publication bias analyses. Results: Eighty potential articles were identified, from which 30 contained sufficient data to enable statistical meta-analysis. From these 30 studies, 18 described a biological, 13 a psychotherapeutic and 9 a contextual intervention, either applied alone or combined. The overall standardised mean difference was 0.671 (SD = 0.051). As shown by sensitivity analysis, this summary effect size is robust. Assessed through subgroup and meta-regression analysis, all tested moderators showed no statistically significant association with the treatment effects. After applying a funnel plot-, a fail-safe N-, and Duval’s and Tweedie’s trim and fill-analysis, we conclude that our meta-analysis does not suffer much from publication bias effects. Conclusions: Several biological, psychotherapeutic and contextual interventions effectively reduce challenging behaviours among persons with intellectual disabilities.