The "Picture Exchange Communication System" (PECS) has emerged as the augmentative communication intervention of choice for individuals with autism spectrum disorder (ASD), with a supporting body of single-participant studies. This report describes a meta-analysis of 16 single-participant studies on PECS with percentage of nonoverlapping data (PND) as the metric of effect size. Results suggest that PECS was moderately effective in establishing mands (PND = 80.1) for 41 participants up to Phase IV of the system. Higher levels of manding were found when PECS was taught to individuals without ASD diagnoses versus those with ASD diagnoses and in single settings versus multiple settings; however, these differences were not statistically significant. For a smaller subset of participants for whom vocalizations were recorded, PECS appeared to facilitate speech, though considerable variability in speech acquisition was evident. While these results support PECS as an evidenced-based communication intervention, they indicate that more research is needed on speech with PECS, to establish the efficacy of PECS when implemented across settings and communicative partners, and to confirm efficacy of Phases IV, V, and VI. (Contains 2 tables.)