The Cohort Consortium is an extramural-intramural partnership formed by the National Cancer Institute (NCI) to address the need for large-scale collaborations to pool the large quantity of data and biospecimens necessary to conduct a wide range of cancer studies. The Consortium, through its collaborative network of investigators, provides a coordinated, interdisciplinary approach to tackling important scientific questions, economies of scale, and opportunities to quicken the pace of research. The Cohort Consortium includes investigators responsible for more than 40 high-quality cohorts involving more than 4 million people. The cohorts are international in scope and cover large, rich, and diverse populations in the United States, Canada, Europe, Asia, the Middle East, and Australia. Extensive risk factor data are available on each cohort, and biospecimens including germline DNA collected at baseline, are available on more than 2 million individuals. Investigators team up to use common protocols and methods, and to conduct coordinated parallel and pooled analyses. More information about the consortium and its collaborators may be found on the website, http://epi.grants.cancer.gov/Consortia/cohort.html.