Peer support presents a unique opportunity for health care planning and management. Clear evidence shows concrete benefits for individuals and systems, including cost-effectiveness. As an important humanizing force in health care, it changes the way we look at health. To bring peer support to diverse populations and settings, the key functions provide a framework for standardization and flexible adaptation. This report sets the course for scalable, feasible implementation that reaches whole populations, engages those too often left behind in health care, improves outcomes as well as quality of life, and reduces unnecessary burden and costs. This report features the evidence of major research funded by Peers for Progress. Together with extensive findings from collaborators and colleagues around the world, the case for peer support is strong and clear. Peer support works and provides an excellent strategy to address present and future health challenges, including engaging those whom health care and prevention too often fail to reach, addressing mental health and its intersections with other health problems, reducing unnecessary and costly care, and improving the health of populations.