PurposeThe purpose of this paper is to explore what worked well in terms of peer involvement in a diverse network of community groups for people affected by mental health problems in Bath and North East Somerset (BANES), UK.Design/methodology/approachA participatory action inquiry approach engaged the network’s key stakeholders (group members, facilitators, and commissioners) in critical reflection on what supported successful groups.FindingsSuccessful groups have six characteristics: mutual support, a positive shared identity, opportunities for taking on roles, negotiated ground rules, skilled facilitation, and a conducive physical environment. Additionally, each group achieved a balance between the following areas of tension: needing ground rules but wanting to avoid bureaucracy, needing internal structure whilst also committing to group activities, balancing leadership with accountability, wanting peer leadership whilst acknowledging the burden of this responsibility, and lobbying for change in mental health services whilst acknowledging the need for support from them.Research limitations/implicationsThe evaluation shows a group’s success is about adaptability and group facilitation is the art of navigating a course through these competing demands above. These insights have informed plans for a practical guide for developing peer led groups and for training of peer leaders in BANES.Originality/valueThis evaluation focuses on self-efficacy. It draws on group members’ own perceptions of what worked best for them to provide transferable learning about how peer led support groups might develop more generally. It can thus inform the growth of a comparatively new kind of community-based support for people with mental health problems and for their carers.