The current meta-analytic review analyzed 43 studies published in English, Chinese, and Japanese to determine the effects of caregiver involvement for promoting communication skills of individuals with ASD and IDD. Tau-U effect sizes, the Kruskal-Wallis H test, and the Dunn post hoc test were employed to calculate for moderator analyses: child age, settings, service delivery formats, and dosages of services provided to caregivers. The overall effect size for family involvement had a moderate effect on child communicative outcomes, as well as on child ages, settings, delivery formats, and dosages of services provided to caregivers of individuals with ASD and IDD. A statistically significant difference was found in children's communication outcomes between the four dosage groups of services provided to caregivers.