Intensive Interaction is an approach to teaching the fundamentals of communication to children and adults who have severe learning difficulties or autism, and who are still at an early stage of communication development. Its simplicity and effectiveness has been one of the major themes in the widespread practitioner dissemination that has taken place during the last twenty years. Despite the human simplicity of the approach, Intensive Interaction relates to, or is influenced in practice by, a wide range of interconnecting theories and academic standpoints. With contributions from leading authorities, Dave Hewett provides a comprehensive and detailed description of the theoretical landscape of a now established methodology. The most prominent related theories and issues are reviewed, with Intensive Interaction set within their contexts.