Well-construction, water-level, and ground-water- quality data were collected by the U.S. Geological Survey during 1989-92 in Prince William County, Virginia. The data are presented on a map, in tables, and in hydrographs to record ambient ground-water quality. Well construction data include descriptions of 182 well sites. Water-level data include measurements from 159 wells that were collected in the spring and fall of 1991 and hydrographs from six of the wells. Ground-water- quality data collected at 87 wells include analyses for major dissolved constituents, trace metals, nutrients, dissolved organic carbon, radon-222, and alkalinity. Environmental or stable isotope analyses were collected at 57 wells and dissolved gas analyses were collected at 18 wells. Field proper- ties were also recorded during sampling.