This article explores risk behaviour in adults with a diagnosis of Asperger's syndrome (AS) or high-functioning autism (HFA) during the transition to adulthood, drawing on interviews with twelve individuals and on two focus groups comprising members of other families affected by autism spectrum disorder (ASD). The authors examine the subtle interplay between engagement in a variety of risk behaviours and the health and wellbeing of particular individuals with ASD. Feelings of anger, hopelessness and self-harming were common responses to bullying and pervasive difficulties with social interaction. There appears to be no clear causal relationship between risk behaviours and transition, which is characterised by protracted and complex period of identity formation. The current orthodoxy of service provision emphasises the importance of integration with the local community, irrespective of the challenges this may present to people with ASD. There is scope for further elaboration of the concept of "emerging adulthood" in relation to people with disabilities in general and people with ASD in particular.