The purpose of this paper is to investigate Keyes¿ (2007) model of mental health, the presence (flourishing) or absence (languishing) of social, emotional and psychological wellbeing, in the context of drug and alcohol misuse and the frequency and pattern of community participation (engaging in society). Design/methodology/approach: Participants were 1,815 individuals (70 per cent male) who entered residential substance misuse treatment provided by The Salvation Army. Questionnaires were completed at intake assessments with The Salvation Army staff. The data were compared with population norms of community participation utilising t-tests, while multiple linear regression was used to examine continuous mental health. Findings: Although participants have lower levels of community participation compared to Australian population norms, those participants who were experiencing flourishing mental health had higher rates of community participation than Australian norms. Keeping in touch with friends and family was the most common form of participation. Informal social connectedness and civic engagement were the strongest predictors of mental health over and above more traditional substance use outcomes such as cravings. Originality/value: This is one of the first studies to describe the relationships between community participation, substance use and mental health in participants seeking treatment for substance misuse. Despite having a drug or alcohol addiction requiring treatment, those participants with flourishing mental health have higher levels of community participation than community norms. Furthermore, community participation predicts mental health. This offers promise for interventions that increase community participation but further research using longitudinal designs is needed to replicate and clarify the direction of these relationships.