Nanotechnology-a term encompassing the science, engineering, and applications of submicron materials-involves the harnessing of unique physical, chemical, and biological properties of nanoscale substances in fundamentally new and useful ways. The economic and societal promise of nanotechnology has led to substantial and sustained investments by governments and companies around the world. In 2000, the United States launched the world's first national nanotechnology program. From FY2001 through FY2012, the federal government invested approximately $15.6 billion in nanoscale science, engineering, and technology through the U.S. National Nanotechnology Initiative (NNI). President Obama has requested $1.8 billion in NNI funding for FY2013. U.S. companies and state governments have invested billions more. As a result of this focus and these investments, the United States has, in the view of many experts, emerged as a global leader in nanotechnology. However, the competition for global leadership in nanotechnology is intensifying as countries and companies around the world increase their investments. Nanotechnology's complexity and intricacies, early stage of development (with commercial payoff possibly years away for many potential applications), and broad scope of potential applications engender a wide range of public policy issues. Maintaining U.S. technological and commercial leadership in nanotechnology poses a variety of technical and policy challenges, including development of technologies that will enable commercial scale manufacturing of nanotechnology materials and products; environmental, health, and safety concerns; and maintenance of public confidence in its safety. Congress established programs, assigned responsibilities, and initiated research and development related to these issues in the 21st Century Nanotechnology Research and Development Act of 2003 (P.L. 108-153). Although many provisions of this act have no sunset provision, FY2008 was the last year of agency authorizations included in the act. Legislation to amend and reauthorize the act was introduced in the House (H.R. 5940, 110th Congress) and the Senate (S. 3274, 110th Congress) in the 110th Congress. The House passed H.R. 5940 by a vote of 407-6; the Senate did not act on S. 3274. In January 2009, H.R. 554 (111th Congress), the National Nanotechnology Initiative Amendments Act of 2009, was introduced in the 111th Congress. The act contained essentially the same provisions as H.R. 5940. In February 2009, the House passed the bill by voice vote under a suspension of the rules. The bill was referred to the Senate Committee on Commerce, Science, and Transportation; no further action was taken. On May 7, 2010, the House Committee on Science and Technology reported the America COMPETES Reauthorization Act of 2010 (H.R. 5116, 111th Congress) which included, as Title I, Subtitle A, of the National Nanotechnology Initiative Amendments Act of 2010. This title was removed prior to enactment. No comprehensive reauthorization bill has been introduced in the 112th Congress. Proponents of the NNI assert that nanotechnology is one of the most important emerging and enabling technologies and that U.S. competitiveness, technological leadership, national security, and societal interests require an aggressive approach to its development and commercialization. Critics of the NNI voice concerns that reflect disparate underlying beliefs. Some critics assert that the government is not doing enough to move technology from the laboratory into the marketplace. Others argue that the magnitude of the public investment may skew what should be market-based decisions in research, development, and commercialization. Still other critics say that the inherent risks of nanotechnology are not being addressed in a timely or effective manner.