A comprehensive field data base is being developed for testing various chemical-transport models of pesticide leaching. Three Federal agencies (U.S. Environmental Protection Agency, U.S. Department of Agriculture, and U.S. Geological Survey) and the University of Georgia's Agricultural Experiment Station established a joint research team to investigate and model pesticide movement in a conventionally tilled corn field in the coastal plain of Georgia. The experimental study design, the monitoring procedures for unsaturated and saturated soil zones, and the data collection methods are presented in the context of a quantitative statistical model testing strategy. Compounds under study include carbofuran (2,3 dihydro-2,2-dimethyl-7-bezofuranyl methylcarbamate), atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5 triazine), alachlor (2-chloro-2'6'-diethyl-N-(methoxymethyl)-acetanilide), and a bromide tracer. Initial application losses were on the order of 15 to 39%. Of the three pesticides, only carbofuran persisted for 4 months and moved to levels as deep as 3 meters. Half-lives were estimated for all compounds on the basis of total mass in the soil profile.