One of the 5 principles of primary health care is public participation. Partnership between professionals and their clients is compatible with this principle. This article describes how professionals and peers can work together in support group interventions. Examples are cited from 3 intervention studies focused on myocardial infarction survivors and their spouses, parents of children with chronic conditions, and older women with disabilities. Each of the support groups entailed co-leadership by and partnerships between peers and professionals. The article describes the characteristics, roles, and training of peers and professionals; data collection involving peers, professionals, and participants; and pertinent intervention processes. Peers and professionals collaborated as co-leaders and partners in 21 support groups in the 3 studies. Participants expressed satisfaction with the leadership of the support groups. Moreover, professional facilitators and peer facilitators each acknowledged the important role and perspective of the other.