This project aims to contribute to the literature on language development of children with co-occurring Down Syndrome and Autism, and the impact of raising these children bilingually vs monolingually. Individuals with DS-ASD have different symptoms to individuals with only one of these disorders, and face additional challenges, including regression of language abilities. Caregivers naturally want to confer every advantage they can, but advice, which is not at all empirically supported, to raise children with DS-ASD monolingually is often given to these caregivers. The relative dearth of literature looking at bilingualism and DS-ASD could be contributing to this problem.