The mental health of young people is a pressing concern in global development. However, there is little research on how young adults report their own mental health. The interview data gathered in this study (n ¼ 74) explored young adults’ well-being during the transition period from care to independent living under an English local authority and in Finland. Participatory action research methods were employed. The interview schedule included 71 open and closed questions, and was analysed by content and summarised using the SPSS software application and Excel tables. The themes concerning mental health and social relationships were divided into three categories: ‘They have been there for me’, ‘My friends are the only ones’ and ‘They just guided me’. Participants who felt they had supportive social networks also felt their mental well-being and security to be better than those who did not. Overall, the findings demonstrated that good, significant social relations provided a sense of security but did not guarantee a positive mental outlook. Exploring young adults’ own evaluations of their social networks provides social work practitioners with sensitive information with which to find ways for young people to support their mental health in their own terms.