Dense nonaqueous phase liquids (DNAPLs) in the subsurface are long-term sources of ground-water contamination, and may persist for centuries before dissolving completely in adjacent ground water. In response to increasing recognition among scientists and engineers that DNAPL contamination is widespread, a two-day workshop concerning DNAPL site characterization and remediation was held in Dallas, Texas on April 16-18, 1991. The workshop was sponsored and organized by EPA's Ground Water Forum, Robert S. Kerr Environmental Research Laboratory, and Office of Solid Waste and Emergency Response, and the University of Waterloo, Ontario, Canada. Professionals from government, academia, and private industry with experience in DNAPL contamination presented papers and participated in discussions concerning the options for characterization and remediation of DNAPL sites. The document was prepared to summarize the main observations and conclusions of the meeting, and draws freely from transcripts, papers, and comments prepared by the participants. A second meeting of the participants was held in Dallas on September 5-6, 1991 to review the draft summary. The summary is intended to be a nontechnical document of general interest to environmental scientists and engineers from Federal, State, and local agencies, universities, and private industry. Readers interested in more specific technical information should consult the extensive list of references compiled in Appendix C. The material presented here represents 'state-of-the-art' information, and, as such, can be expected to change as the science progresses.