Objective: To examine the usefulness of the Strengths and Difficulties Questionnaire (SDQ) as an outcome measure for patients referred to a child and adolescent mental health service (CAMHS). Methods: This was a prospective study of new CAMHS attendees. Questionnaires were completed by clinicians, parents, teachers and children (if aged 11 years or older) at initial attendance and after approximately 6 months. Results: At 6-month follow up, positive change was detected on the SDQ. There was a significant reduction in the 'total difficulties' score as rated by parents, teachers and children. This positive change corresponded to a significant reduction in the clinician-rated Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA) scores. Furthermore, there were lowered levels of perceived difficulties and burden on the SDQ impact supplement, and a decrease in the overall impact score. Conclusion: The SDQ is a useful outcome measure. The HoNOSCA and SDQ complement each other because they provide measures of change from the clinician, the parent and the child.