 In the UK young people attending child and adolescent mental health services (CAMHS) are required to move on, either through discharge or referral to an adult service, at age 17/18, a period of increased risk for onset of mental health problems and other complex psychosocial and physical changes. CAMHS transitions are often poorly managed with negative outcomes for young people. Better preparation may improve outcomes and experience. This study aimed to co-produce, with young people who had transitioned or were facing transition from CAMHS, a CAMHS Transition Preparation Programme (TPP), deliverable in routine NHS settings.