Playas (dry lake beds), the flat central portions of desert basins, are landforms which have unique properties. Most of those in the U.S. were sites of larger Pleistocene lakes, and are characterized by fine-grained lacustrine silt and clay, with secondary saline, sulfate, and carbonate minerals. The playa surfaces are essentially level, but hydrologic, tectonic, and climatic forces are continually modifying them. A variety of surface features representing a range of influence of the arid environment have been noted; these features are subject to change in response to a changing environment. Playa basins have been studied in the field using the geophysical methods of gravity, seismology, electrical resistivity, and magnetism. This report is a collection of six individual papers discussing the environment and surface features, mineralogy, hydrology, structure, geophysics, and airphoto features of playas. (Author).