Community participation is considered important in primary health care development and there is some evidence to suggest it results in positive health outcomes. Through a process of synthesising existing evidence for the effectiveness of community participation in terms of health outcomes we identified several conceptual areas of confusion. This paper builds on earlier work to disentangle the conceptual gaps in this area, and clarify our common understanding of community participation. We conducted a research synthesis of 689 empirical studies in the literature linking rural community participation and health outcomes. The 37 final papers were grouped and analysed according to: contextual factors; the conceptual approach to community participation (using a modification of an existing typology); community participation process; level of evidence; and outcomes reported. Although there is some evidence of benefit of community participation in terms of health outcomes, we found only a few studies demonstrating higher levels of evidence. However, it is clear that absence of evidence of effect is not necessarily the same as absence of an effect. We focus on areas of debate and lack of clarity in the literature. Improving our understanding of community participation and its role in rural primary health care service design and delivery will increase the likelihood of genuine community-health sector partnerships and more responsive health services for rural communities.