This final document describes the design and format of EPA's Nanoscale Materials Stewardship Program (``the program'') for nanoscale materials under the Toxic Substances Control Act (TSCA). Based on ideas in the concept paper, written public comments, comments at public meetings, and scientific peer consultations on material characterization and risk management practices, EPA has developed this document to provide the final description and format of the program. EPA will consider refinements to the program over time based on experience and additional feedback from participants. POC is Colby Lintner, Regulatory Coordinator, Environmental Assistance Division (7408M), Office of Pollution Prevention and Toxics, Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone number: (202) 554-1404; e-mail address: TSCA-Hotline@epa.gov (Federal Register: January 28, 2008 [Notices], Page 4861-4866).