Has language developed to serve as a system of communication or one of thought? While language is clearly an excellent tool for communication, the possible contribution of higher order cognitive processes other than language to communication may provide insights on how we think about language evolution. Studies show that bilingualism improves communication skills, possibly due to boosting domain general processes, thus suggesting a divide between communication and formal language. However, to date little attention has been paid to bilingual atypical child (...) populations presenting asymmetric developmental delays in language and communication skills. In this study, we explore the language-communication divide in bilingual and monolingual children diagnosed with High Functioning Autism (HFA), displaying primary communication difficulties, and those with Specific Language Impairment (SLI), displaying primary language difficulties. Children were tested on language, cognitive control, Theory of Mind (ToM), social comprehension and verbal communication. Results demonstrate that bilingual children with HFA exhibit enhanced cognitive control, ToM and social comprehension, which in turn improve their verbal communication as compared to their monolingual peers with HFA. On the other hand, no boost emerges in bilingual children with SLI, be it in cognitive control or ToM, though a weaker advantage (relative to the children with ASD) can be observed in their verbal communication skills, with significant mediation from social comprehension. The overall evidence suggests that language, though useful for communication, is not sufficient for communication, and may arguably not have evolved primarily for communicative purposes. (shrink)