A 4-year follow-up compared the long-term effects of two treatments for severely conduct disorder children referred to a Child and Adolescent Mental Health Service (CAMHS). Forty-two families received either the standard CAMHS treatment or a more intensive intervention. The intensive treatment involved a unit-based component for parents to practise new child management strategies. At the 6-month follow-up the intensive treatment group showed significant improvements on all measures of child behaviour and maternal mental health and improvements remained significant at the 4-year follow-up. By contrast, initial improvements for the standard treatment group, which were significant on only two measures, were not significant at the 4-year follow-up. The results suggest that the intensive treatment was advantageous in bringing about long-term improvements for these families. They also add to the growing evidence that interventions involving the rehearsal of child management strategies have better outcomes than those using more didactic methods of parent training.