CCFRC aims to collect pedigree information, epidemiological data, and related biological specimens from participants with and without colorectal cancer or family history of the disease, as a resource for studies on colorectal cancer; and to identify a population at high risk of colorectal cancer that could benefit from preventive strategies. Over 42,000 participants from more than 15,000 families have completed the baseline questionnaire since the study began in 1998. This includes population-based and clinic-based cohorts recruited at seven institutes in the United States, Canada and Australasia. Participants are followed up with questionnaires every 4 to 5 years, and passive follow-up is conducted regularly through data linkage and mail contact with participants.