BackgroundIn 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.MethodsEighteen young people, aged 17–22, from three UK National Health Service (NHS) mental health foundation trusts participated in creative, participatory research workshops. Seven parents completed short questionnaires. Thirty clinical staff from two trusts took part in workshops to ensure deliverability of young people’s ideas. Young people were offered co-research opportunities.ResultsMost young people felt anxious, fearful and uncertain on leaving CAMHS and perceived mental health services as uncaring. Participants outlined transition procedures and drafted a range of preparation activities, centred around dedicated Transition Peer Support and a transition booklet, which should be offered to all CAMHS leavers, irrespective of discharge or transfer to an adult service. Preparation should aim to build confidence to help young people take responsibility for themselves and flourish in the adult world: coping or getting through it was not enough. Some clinicians also felt anxious at transition and recognised the potential impact on young people of poor communication and lack of understanding between services. Parents would appreciate help to support their offspring during the transition period. Clinicians cited lack of funding and inflexible NHS procedures and policies as potential barriers to the implementation of young people’s ideas. Nine young people took up co-research opportunities.ConclusionsMental health services underestimate the anxiety of CAMHS leavers. Young people have clear ideas about the preparation they require to leave CAMHS with the confidence to take responsibility for their own health care. Close collaboration of NHS staff and researchers facilitates the implementation of research findings.