Background: The transition between child and adult services should aim to support young people into the next stage of their life in a way that optimises their function. Yet financial, organisational and procedural barriers to continuity of care often hamper smooth transition between child and adult services. Aim and method: We reviewed studies of transition from child to adult mental health services, focusing on: (i) rates of referrals and referral acceptance; (ii) barriers and facilitators of successful transition; (iii) continuity of care during and post-transition; and (iv) service users’ experience of transition. Studies were identified through systematic searches of electronic databases: PsychINFO, Medline, Embase and Child Development and Adolescent Studies. Findings: 47 papers describing 43 unique studies met inclusion criteria. Service provision is influenced by previous history and funding processes, and the presence or absence of strong primary care, specialist centres of excellence, and coordination between specialist and primary care. Provision varies between and within countries, particularly in whether services are restricted to “core” mental health or broader needs. Unsupportive organisational culture, fragmentation of resources, skills and knowledge-base undermine the collaborative working essential to optimise transition. Stigma and young people’s concerns about peers’ evaluation often prompts disengagement and discontinuation of care during transition, leading to worsening of symptoms and later, to service re-entry. Qualitative studies reveal that young people and families find the transition process frustrating and difficult, mainly because of lack of advanced planning and inadequate preparation. Conclusion: Despite increasing research interest over the last decade transition remains “poorly planned, executed and experienced”. Closer collaboration between child and adult services is needed to improve the quality of provision for this vulnerable group at this sensitive period of development.