Previous research examining the clinical phenomenology of obsessive–compulsive disorder (OCD) has provided some evidence that OCD might be associated with different clinical correlates at different stages of development. In particular, there appears to be a bimodal distribution in terms of the age of onset of the disorder, a male predominance during childhood and adolescence compared to adulthood, stronger familial aggregation of OCD in early onset cases, and differences in the types of symptoms and the patterns of comorbidity across age groups. This study assessed the continuity in clinical presentation of OCD across three distinct age groups: children, adolescents and adults. It was hypothesised that the sample of children would be predominantly male, and would have a higher familial aggregation of OCD and/or anxiety/depression in first-degree relatives. It was further hypothesised that there would be significant age-related differences in terms of specific symptoms, patterns of comorbidity, OCD severity, functional impairment, and level of insight and distress. The results of this study support the developmental heterogeneity hypothesis, with significant differences occurring across age groups on a number of clinical features of OCD including age at onset, symptoms experienced, comorbidity, severity, insight and impairment. Implications of the findings and future directions for research in this area are discussed.