This contract provides the National Institute of Environmental Sciences and the Division of the National Toxicology Program (NIEHS/DNTP) with a wide variety of collaborative pathology services that best support the DNTP's evolving toxicologic research and chemical/agent testing mission. The services provided range from traditional GLP-compliant toxicologic pathology support and the conduct of the Pathology Peer Review (Quality Assessment and Pathology Working Groups Reviews) to the development and/or refinement of special pathology-based procedures and innovative technologies responsive to investigative research concerns and mechanistic issues. Because the DNTP's service needs are largely unpredictable, adequate numbers of DNTP-qualified and experienced pathologists, proficient technical personnel and support staff must be committed on an as-needed basis to be immediately responsive to the collective pathology requirements of eight individual task assignments, including several involving client-site services.