Young adults’ mental health is a critical area of concern, with early intervention known to reduce the risk of enduring psychological difficulties later in life. The NHS England Long Term Plan’s increased funding for Children and Young People’s Mental Health Services (CYPMHS) signals a system-level prioritisation of youth mental health that determines service availability and the quality of transitions into adult care. This thesis contributes to that agenda by exploring under-researched dimensions of young adults’ mental health across distinct populations. Part One presents a systematic review examining unaccompanied refugee minors’ (URM) sense of belonging during their transition to adulthood. The findings suggest that belonging for URM is dynamic and transcends time and place; interweaving past, present, and future into a tapestry shaped by their changing circumstances. Part Two presents an empirical study exploring Middle Eastern North African (MENA) young adults’ experiences of mental health recovery; an under-represented group in both research and mental health services. The findings indicate that recovery was a process of forced self-reliance, shaped by limited support from parents, peers, and formal services. Recovery was a process of relational and emotional negotiation: reconfiguring social networks, confronting inherited shame, and learning to live with pain that could not be externally resolved. Recovery, in this context, was a redefinition of selfhood under conditions of silence, stigma, and cultural constraint.