This paper provides an overview of five review studies that analyzed 92 single subject studies on the effectiveness of major augmentative and alternative communication (AAC) systems for individuals with developmental disabilities including autism. This paper offers recommendations useful for AAC decision-making points. Research on the effectiveness of main communication systems over the last 25 years has yielded mixed and inconsistent results on communication and preference outcomes. The heterogeneity of a large quantity of studies involved various research designs, participants, and multiple components is a major concern with the review studies. It is recommended to conduct more focused syntheses of empirical studies in terms of research designs, target population, and program components.