A high proportion of people with developmental disabilities engage in challenging behavior compared to the general population (McClintock, Hall, & Oliver, 2003). Functional Communication Training (FCT) is an is an evidence-based intervention to address challenging behavior (Heath et al., 2015), but many people remain unable to access effective interventions like FCT. One strategy to increase access is to train parents to be interventionists for their children. The present study is a meta-analysis of studies examining parent-implemented FCT. Procedures were registered with PROSPERO prior to data extraction (Registration # CRD42018100912, Pennington, 2018). The study addresses the following questions: (1) What is the overall effect of parent-implemented FCT on challenging behavior and communication?; (2) What are the characteristics of participants, implementers, and interventions in parent-implemented FCT studies, and to what extent do those characteristics moderate outcomes?; (3) Do parents implement FCT with fidelity, and how were parents trained or coached?; and (4) To what extent do included studies meet quality indicators? I used a multi-level, mixed effects meta-analysis to examine the effects of parent-implemented FCT on challenging behavior for 53 participants in 21 studies, and on communication for 29 participants in 14 studies. Overall, FCT had a moderate to large effect size for reducing challenging behavior and a large effect size for increasing communication. No significant moderators were found for participant or coaching characteristics. For intervention characteristics, implementing the intervention in natural settings was significantly associated with an increased effect size. These results indicate that parent-implemented FCT is an effective intervention across various participant, intervention, and coaching characteristics. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]