This book documents recent dramatic breakthroughs and prospects for even more important future developments in a wide variety of fields and applications of science and technology related to `nanotechnology', all involving the control of matter on the nanometer-length scale, that is, at the level of atoms, molecules, and supramolecular structures. As the twenty-first century unfolds, nanotechnology's impact on the health, wealth, and security of the world's people is expected to be at least as significant as the combined influences in this century of antibiotics, the integrated circuit, and human-made polymers. The book covers fundamental scientific issues for nanotechnology and reviews progress in the development of the necessary tools for nanotechnology research and applications (e.g. theory, modeling and simulation, experimental methods, and instruments such as scanning probe microscopes). It also surveys a wide variety of current and potential application areas of nanotechnology, including: dispersions, coatings, and large surface area structures; nanodevices, nanoelectronics, and nanosensors; materials science and applications of bulk nanostructured materials with novel properties; biology, medicine, and healthcare; and energy, chemicals, and environmental science. The book incorporates the views of leading experts from U.S. government, academia, and the private sector. It reflects the consensus reached at a workshop held in January 1999, and detailed in contributions submitted thereafter by members of the U.S. science and engineering community. It describes challenges that are posed and opportunities that are offered by nanotechnology and outlines the steps that must be taken in order for humanity to benefit from the advances that are envisioned. This emphasizes three crucial areas: developing a balanced research and development infrastructure, advancing critical research areas, and nurturing the scientific and technical workforce of the next century.