It is nearly 30 years since the publication of the edited book by Rutter and Martin (1972), The child with delayed speech (London: Heinemann), which drew attention to the two-way relationship between language and behaviour. In the book the mechanisms whereby psychiatric disorders can have an involvement with language development were identified. Also, Mike Rutter suggested various ways in which delayed language development could impinge upon other aspects of psychological development. The current issue of the JCPP has a number of papers that examine the relationship between language development and aspects of cognition and behaviour. These include a long-term follow-up for a group of individuals with receptive language disorder who were first studied at about the time that the 1972 book was published.