The National Nanotechnology Initiative (NNI) was created in 2000 to focus and coordinate the nanoscience and nanotechnology research and development (R&D) activities being funded by several federal agencies. The purpose of the NNI is to marshal these research activities in order to accelerate responsible development and deployment of nanotechnology for economic benefit and national security. To take stock of the progress of the NNI, Congress, in P. L. 108-153, the 21st Century Nanotechnology Research and Development Act, directed the National Research Council to carry out a review of the program every three years. This report presents the results of the first of those reviews, which addresses the economic impact of nanotechnology developments and provides a benchmark of U.S. R&D efforts relative to those undertaken by foreign competitors. In addition, the report offers an assessment of the current status of responsible development of nanotechnology and comments on the feasibility of molecular self-assembly.