OBJECTIVE: Outcomes are presented from a public mental health early intervention program for children aged 5-9 years with disruptive behaviours. METHOD: This was a school-based intervention initiative, delivered within a psychiatric child and adolescent mental health service and includes child, parent and teacher components. Participants were 235 children selected via school-based population assessments. RESULTS: A baseline period was used as a form of control that would demonstrate the stability of problem behaviours. Results showed that during a 26-week baseline period, teachers reported increasing levels of problem behaviour, and that the behaviour was creating increased difficulty in the classroom. The shorter 7-week baseline also showed the difficult behaviours were ongoing. Following the intervention, significant improvements in children's behaviour were seen on the Strengths and Difficulties Questionnaire reported by parents (η(2) = 0.30) and teachers (η(2) = 0.23), and on the parent Eyberg Child Behaviour Inventory (η(2) = 0.35), and teacher Sutter-Eyberg Student Behaviour Inventory (η(2) = 0.22). CONCLUSION: The outcomes show promising results from an early intervention program delivered in schools by a public mental health service and are discussed within the context of dissemination of evidence-based programs though mental health services.