This paper begins by identifying certain features of sequential understandings which are oriented to within the interaction of typically developing young children from about the age of2;0 onwards. It then examines literature bearing on the interaction of children with autism, Asperger's syndrome, and pragmatic impairment which suggests a diminished regard on their part to local, on-line details of their interaction and a heightened involvement with bodies of knowledge which they bring with them to any occasion. These themes are explored in the context of the ways in which these children initiate interaction, ways through which they make conversational contributions, and with regard to interactional features which generate distress. The paper draws out how the contrasting interaction profiles of typically developing children and those with pragmatic disabilities can have implications for our ways of understanding both the development of children with autism and the acquisition of cultural knowledge by typically developing children.