How do deaf children acquire sign language? The first point to stress is that the sign system they are acquiring is a formal language in the full sense of the word. Deaf individuals across the globe use sign languages as their primary means of communication. These sign languages assume all of the functions of spoken languages. They are used to communicate about the here-andnow, but also about worlds that are not present. They are used to direct, to advise, to declare, to joke, to pun-any functions that spoken language serves can be, and are, filled by sign language.