Public involvement in health program planning has been taking place for many years, and has provided a precedent for the emergence of public involvement in research conducted since the early 1990s. Such involvement is now widely seen in breast cancer research, due to the large public concern and major social movement activity. This article reviews current practices and general models of public involvement in research and constructs a prototype. The authors interviewed researchers, program officers, and laypeople in order to understand the obstacles, processes, and benefits. They conclude that public involvement has major ramifications for the democratization of science and the construction of knowledge by teaching lay people about science and sensitizing researchers to concerns of the public. There is growing support on the part of scientists and government agents for public involvement.