This step-by-step guide to Brief Behavioural Activation (Brief BA) provides everything practitioners need to use this approach with adolescents. It is suitable for new practitioners as well as those who are more experienced. Brief BA is a straightforward, structured and effective intervention for treating adolescents showing symptoms of depression, focusing on helping young people to recover through doing more of what matters to them. This practical manual contains guidance on how to deliver Brief BA at every stage, photocopiable activities and worksheets for the client and their parents, and a section on the research and theory behind the approach. It includes information and advice on how to assess adolescent depression, get to know the young person and their priorities better and help them to do more of what matters.