Mental disorder is common amongst young adults and is associated with many adverse outcomes. Data, however, indicate that young adults are particularly unlikely to seek help for such distress. This paper describes a qualitative study of 23 young adults (aged 16 to 24 years) with mental distress. Interviewing was used to obtain detailed narratives of illness behaviour and to explore reasons for non-help-seeking. Help-seekers and non-help-seekers were interviewed. The findings allowed development of an explanatory model - the cycle of avoidance (COA) - which contributes towards attempts to provide a dynamic understanding of help-seeking behaviour. Dominant approaches tend to be deterministic and static and to account for non-help-seeking in terms of 'barriers' to care, which although easily translated into targets for policy intervention, are superficial representations of complex issues. The COA conceptualises help-seeking as a circular process and offers a model of 'non-help-seeking' in which lay conceptions of mental distress, the social meanings attached to 'help-seeking' and treatment, and the purposeful action of individuals, assume central importance. Although derived in the context of young adulthood and mental distress, this model may have wider applicability as a theoretical template for explaining non-help-seeking in other age groups and conditions, and other illness behaviours.