Piezoelectricity was first discovered by the Curie brothers in 1880. During the 1940s, piezoelectric ceramic materials were first used in commercial devices, and new materials and other applications have continued to develop over the years. Most recently, however, relaxor-based ferroelectric single crystals have been produced. In most cases, these single-crystal material properties, exceed those of conventional piezoelectric ceramics. The purpose of this study was to determine the current commercial and military uses of the piezoelectric materials, the properties that are important to these uses, and the impact of substituting single-crystal materials for the piezoelectric materials. Service and Defense agency piezoelectric development programs are discussed, as is the possibility of restructuring these programs to take advantage of the single-crystal materials. Novel military uses for single-crystal piezoelectric materials are given, and important commercial applications for single-crystal piezoelectric materials are identified. Finally, issues such as design modifications needed to produce devices using the single crystals are addressed.