The Purdue Water Resources Research Center, in conjunction with the Office of Health and Environmental Research of the U.S. Department of Energy, cosponsored a meeting on the current uses of and future needs for supercomputers in hydrology at Purdue University, West Lafayette, Ind., September 10–12, 1985. The charge of the seminar, “Supercomputers in Hydrology: Future Directions” (the first meeting of its kind), was to evaluate the need for large-scale vector and parallel processing machines and their peripherals in the hydrologic sciences with emphasis on subsurface hydraulics. The seminar was attended by about 50 leaders from academia, industry, and government. While the charge of the seminar was to specifically deal with hydrologic applications of supercomputers, the conclusions drawn at the meeting apply equally well to many other fields of science and technology.