Abstract:  Data on the benefits of using geographic information systems (GIS) technology are rare.  The U.S. Geological Survey (USGS) has developed a model to predict the benefits of using GIS technology.  The USGS model focuses on the complexity of a GIS application as the key factor influencing the level of benefits.  Three different aspects of complexity are input to a model consisting of a pair of multiple regression equations.  The equations explain from one-half to three-fourths of the measured variation in GIS benefits and present a powerful tool for improving the quality of GIS cost/benefit studies.