Although it is assumed that volunteers make an extremely important contribution to organizations and the community, studies that examine their direct impact are scarce. Using quantitative and qualitative data collected from clients, volunteers and staff at the Philadelphia Ronald McDonald House, examined is the impact of volunteers on the organization, the clients and on themselves. Volunteers had a high direct and indirect impact on recipients, including on their attitudes toward volunteering and their future behavior. Volunteers gained intrinsic and extrinsic benefits and, as expected, their participation had a positive impact on the organization. The study contributes to the body of knowledge on social impact and volunteering.