We used framework analysis to investigate the utility of pervasive developmental disorder diagnoses, interviewing young people (aged 9-16 years) with high-functioning autistic disorder (AD) and Asperger's disorder (AsD), and their parents. Twenty two participants from ten families described both gains and costs resulting from diagnosis. Perceived advantages of AD and AsD diagnosis were increased understanding and practical support, and parental empowerment. Disadvantages included the effects of stigma and concerns about validity. Participants tended to consider AsD and AD as interchangeable terms. Findings suggest that the utility of AD and AsD depends upon both their validity and how these diagnoses are received in their cultural, economic and legislative context. Improvement of post-diagnostic services will improve the utility of AD and AsD.