An "assurance," is a document negotiated between an institution and the Department of Health and Human Services (HHS) in accordance with HHS regulations. For research involving human subjects conducted by HHS or supported in whole or in part by HHS, the HHS regulations require a written assurance from the performance-site institution that the institution will comply with the HHS protection of human subjects regulations [45 CFR part 46]. The assurance mechanism is described in 45 CFR 46.103. Once an institution's assurance has been approved by HHS, a number is assigned to the assurance. The assurance may be for a single grant or contract (a "single project assurance"); for multiple grants ("multiple project assurances" - formerly called "general assurances"); or for certain types of studies such as oncology group studies and AIDS research group studies ("cooperative project assurances"). The Office for Human Research Protection (OHRP) is responsible for implementing the HHS regulations. The address and telephone number for OHRP are: 1101 Wootton Parkway, The Tower Building, Suite 200, Rockville, MD 20852; Toll-Free Telephone within the U.S.: (866) 447-4777, Telephone: (240) 453-6900, FAX: (240) 453-6909.