Functional communication training (FCT) is one of the most common treatments for challenging behavior and is considered an empirically supported practice for children and adolescents with autism spectrum disorder (ASD). However, no previous systematic review has evaluated the quality of FCT for adults with ASD, and the empirical support for this practice among adults is unknown. The purpose of the current review was to synthesize the extant research, including a quality appraisal of the literature on the use of FCT to treat challenging behavior for adults with ASD. We identified 20 studies that evaluated the efficacy of FCT in reducing challenging behavior for adults with ASD. The quality of each article was evaluated based on the What Works Clearinghouse design and evidence standards. Following the quality and evidence evaluations, eight studies, including eight experiments, were found to have "moderate" or "strong evidence" of effectiveness. The current body of literature provides some evidence for the efficacy of FCT in reducing challenging behavior for adults with ASD, but additional research in this area is warranted.