This study evaluates the work of a multi-disciplinary Behaviour Support Team developed to support schools in managing problematic behaviour. An evidence base to inform future service delivery is developed, using a model of evaluation which incorporates both quantitative, outcome data and more explanatory qualitative data, incorporating the views of service users. Focusing on the first year of service delivery, interventions are evaluated as effective by client schools and positive changes in pupil behaviour are demonstrated. The mechanisms contributing to successful interventions are analysed, including the importance of maintaining a collaborative and systemic approach to problem resolution. The evaluation suggests ways in which educational psychologists working in multi-disciplinary teams can enhance schools' capacity to manage challenging behaviour. (Contains 2 tables and 3 figures.)