Environmental causes are thought to be the etiology of most colorectal cancers (sporadic colorectal cancer). However, about 10% of the cases result from one of two well-defined forms of hereditary colorectal cancer: hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis. The development of intervention/prevention strategies for patients with newly diagnosed colon cancer and their families at high risk for hereditary colon cancer was framed in the questions: "Who is the target?" and "How to identify those at high risk"? There is agreement that genetic analysis for hereditary colorectal cancer holds tremendous promise but that it requires the development of highly structured protocols to ensure that genetic testing is a positive experience for patients at high risk. Appropriate strategies to identify high-risk patients would include recruiting minority (ethnic, racial, and socioeconomic) populations into these studies. Implementation of the protocol would begin with primary-care physicians working with cancer prevention centers in a network to achieve informed consent, to obtain bank-blood samples for genotyping, and to provide the social support and genetic counseling necessary to achieve the goal of a positive experience in cancer prevention. Initial studies would be directed at the known hereditary colorectal cancer groups, including familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer.