Consumer participation in the planning and delivery of health services is recommended and promoted to improve access, quality of care and health outcomes despite questions about the evidence of its impact. There are also significant barriers to participation by certain groups in our community in both their own care and in broader decision-making processes. This paper examines the evidence of the impact of consumer and community participation in health services and the difficulties of engaging more marginalised groups. It proposes three challenges to be met in realising the promise of consumer and community participation: 1) building the capacity of consumers and the community to influence 2) building the capacity of the health system to accept and value their views, and 3) providing opportunities for the most marginalised in society to be heard. In meeting these challenges to consumer and community participation, researchers and practitioners also need to work together to find better ways to measure its impact.