The U.S. Geological Survey, through its Toxic Waste-GroundWater Contamination Program, is undertaking an interdisciplinary research study of groundwater contamination by chlorinated solvents and associated contaminants. The purpose of the study is to gain a better understanding of the chemical, physical, and biological processes that affect the movement and fate of these contaminants in ground water. The study is being conducted at Picatinny Arsenal, New Jersey, where metal-plating and metaletching wastes have contaminated part of the glacial stratified-drift aquifers. This paper describes major areas of research at the site, including: (1) distribution and movement of chlorinated solvents in ground water, (2) behavior of chlorinated solvents in the unsaturated zone, (3) geochemistry of the contaminated ground water, and (4) microbial transformations of chlorinated solvents. This paper also describes objectives and plans of action for these areas of research.