The article considers the nature of the presumed social play deficit in autistic spectrum disorders (ASDs). The nature of play and its typical development is outlined and discussed in relation to play development in ASDs. It is suggested that social play is a confluence of two strands of development that are affected in autism: social and emotional development, and the cognitive development of play. It is shown that social play develops in a transactional way and in ASDs initial social difficulties prevent the development of social interaction, with its role in eliciting and enriching spontaneous play. At the same time, cognitive and affective difficulties prevent the play of children with autism developing to the extent of attracting other children and being of a complexity from which social play might develop. This cycle of impoverished play opportunities for children with ASDs may be broken through direct teaching and there are encouraging models of teaching social play with some success.