Children with antisocial, aggressive and disruptive behaviour problems are among the most frequent referrals to mental health services. These young people and their families present with a range of adverse contextual factors and can prove challenging to engage. We examined the characteristics of children with conduct problems, treatment participation, and the impact of telephone reminder calls. Consecutive referrals (N=262) to two child and youth mental health services were randomly assigned to either a reminder call condition or service as usual. In comparison to referrals without conduct problems, conduct problem children presented with greater sources of psychosocial adversity, attended fewer initial appointments and were at greater risk of treatment refusal. Importantly, telephone reminder calls significantly increased treatment attendance, though only for participants with elevated conduct problems. Telephone reminder calls, however, had no impact on treatment refusal, regardless of conduct problem status. The findings highlight a straightforward approach for enhancing treatment participation among a group that has been challenging for mental health services.