Background: The number of people struggling with vulnerability to mental health difficulties is increasing worldwide, and there is a need for new interventions, to prevent more people from developing serious mental illnesses. In recent years, peer support has been suggested as a key element in creating person-centered interventions in mental health services. However, the evidence for peer support is not yet established. We aim to investigate the effect of a 10-week peer-support intervention "Paths to EvERyday life" (PEER) added to service as usual (SAU) versus SAU alone in a Danish municipality setting.

Methods: A two-armed, investigator-initiated, multi-municipal, parallel-group superiority trial to investigate the effectiveness of the PEER intervention added to SAU compared to SAU alone. A total of 284 participants will be recruited from the municipal social services in the participating municipalities and by self-referrals and randomly assigned to (1) the PEER intervention added to SAU or (2) SAU. The primary outcome is a self-assessed personal recovery (Questionnaire about the process of recovery (QPR-15)) at end of the intervention. The secondary outcomes are self-assessed empowerment (Empowerment Scale Rogers (ESR)), quality of life (The Manchester Short Assessment of Quality of life (MANSA)), and functioning (Work and Social Adjustment Scale (WSAS)).

Discussion: This trial will test a new community-based peer-support intervention, and if the intervention proves to be effective, the goal is that future integration of this intervention will improve individual recovery and mental health and reduce the societal burden of individuals seeking municipal social support and/or mental health services.