The mission of the NIST Physics Laboratory is to support U.S. industry, government, and the scientific community by providing measurement services and research for electronic, optical, and radiation technology. In this respect, the laboratory provides the foundation for the metrology of optical and ionizing radiations, time and frequency, and fundamental quantum processes, historically major areas of standards and technology. The panel on physics visited the six divisions of the laboratory and reviewed a selected sample of their programs and projects. This book finds that the overall quality and productivity of the Physics Laboratory are comparable to or better than those of other peer institutions, an accomplishment that is being achieved with an infrastructure that is smaller in both size and funding than the size and funding of most national and agency laboratories in the United States.