The Diagnostic Interview for Social and Communication Disorders (DISCO) is a schedule for the diagnosis of autistic spectrum and related disorders and assessment of individual needs. It enables information to be recorded systematically for a wide range of behaviours and developmental skills and is suitable for use with all ages and levels of ability. In addition to helping the clinician to obtain a profile of each individual's pattern of development and behaviour, the DISCO also enables identification of specific features found in autistic spectrum disorders that are relevant for use with established diagnostic systems. This paper describes the historical background of the DISCO, outlines its structure and reports the results of an inter-rater reliability study with parents of 82 children aged 3 to 11 years with autistic spectrum disorder, learning disability, language disorder or typical development. Inter-rater reliability for the items in the interview was high (kappa coefficient or intra-class correlation at .75 or higher). This level of agreement was achieved for over 80% of the interview items.