The aim of this review was to critically synthesize barriers and facilitators to the use of AAC systems by children with autism spectrum disorder (ASD) and their communication partners. Qualitative data related to barriers and facilitators were synthesized from 42 studies located using a systematic search. A diverse range of studies was examined in order to identify the span of barriers and facilitators reported in the literature. Included studies comprised quasi-experimental, non-experimental, and qualitative study designs. The full range of unaided, low-tech aided, and high-tech aided AAC systems were reported across the included studies. The critical synthesis identified 5 themes to which barriers and facilitators are related: (a) Intervention Services and Service Providers, (b) AAC Systems and Technologies (c), Communication Partners of Children with ASD, (d) Parents of Children with ASD, and (e) Children with ASD. The findings suggest that barriers and facilitators to the use of AAC vary across individuals, AAC modalities, and environments. By identifying barriers and facilitators to the use of AAC experienced by children with ASD and their communication partners, service providers might be better equipped to support these children and their communication partners. Clinical implications and future research directions are discussed.