BACKGROUND: During transition between Child and adolescent psychiatry (CAP) and General adult psychiatry (GenP) young adults with mental illness face multilevel transitions along with a risk for disruption in continuity of care. Rigid boundaries between the disciplines can be a disadvantage and to decrease the risk transition planning and cooperation are needed.AIM: The aim of this study was to describe professionals’ experiences and views of the transition process from CAP to GenP. METHOD: Data were collected through six focus group discussions with professionals from both CAP and GenP. RESULTS: Data were analysed by content analysis with an deductive approach based on Meleis' middle-range theory of transition. The results showed that young adults were undergoing developmental transitions simultaneous with situational transitions, and they were expected to take responsibility despite they still were in need of support. A gap in transition between CAP and GenP arises when different perspectives, i.e. family and individual perspective, and care cultures meet in a complex process. Lack of knowledge, a mutual understanding and cooperation could also increase the gap. To be able to support the young adult the professionals suggested an individual approach in the transition process.CONCLUSIONS: It is important that professionals at both CAP and GenP focus on transition issues to support young adults to reach a successful transition and adjust to the new situation as adults and user of health care at GenP. Cooperation, transition planning, and a mutual understanding of care can support young adults in transition from CAP to GenP.