The Report on Carcinogens (RoC) is a scientific and public health document that identifies substances that pose a cancer hazard for people living in the United States. It is a congressionally [section 301 (b) (4) of the Public Health Service Act] mandated document prepared by the National Toxicology Program (NTP) for the Secretary of the U.S. Department of Health and Human Services. Substances considered by the NTP for possible listing or delisting in the RoC are evaluated by a rigorous scientific review process, which includes external and government scientific input, opportunity for public comment, and external peer review. Substances are listed in the RoC as either known or reasonably anticipated to be a human carcinogen. The current contract was established to provide support for the preparation of scientific documents, convening review meetings, and for the preparation of the final RoC. These projects require that the Contract staff be composed of individuals with expertise in different scientific disciples (toxicology, genetic toxicology, cancer biology, exposure assessment, and epidemiology).