Group work, such as peer support and health promotion is an important strategy available to comprehensive primary health care. However, group work and how it contributes to the goals of comprehensive primary health care has been under-researched and under-theorised.In this five year study we partnered with seven Australian primary health care services, and drew on service reports, two rounds of staff interviews (2009-2010 and 2013, N=68 and 55), 10 community assessment workshops (N=65), a client survey (N=315), and case tracking of clients with diabetes (N=184, plus interviews with 35 clients, and 5 practitioners) and clients with depression (N=95, plus interviews with 21 clients, and 11 practitioners). We conducted a rapid literature review of existing research on group work, and developed a model showing a group work reinforcing cycle. We examined the nature of the groups run, and the benefits staff and clients perceived.Benefits were grouped into four main themes: 1) social support, including for clients of the Aboriginal services, opportunities to celebrate their cultural identity, 2) improving skills and knowledge, 3) increasing access to services, and 4) empowerment and solidarity CONCLUSIONS: The perceived collective and individual benefits aligned with a comprehensive primary health care vision. However, the individualism stressed by neoliberal-driven health policy threatened the provision of group work and its potential collectivist benefits.There are multiple benefits of group work in primary health care that cannot be achieved through individual work, highlighting the importance of policy and organisational support for group work.