Geographic information systems (GIS) are a special case of information systems with a capability to integrate spatial and descriptive data. As GIS enter into mainstream business applications, understanding how they are similar and different from more familiar information systems such as DSS can be useful. An attempt is made to converge on a definition of GIS. The potential for many decisions to be viewed as spatially (and temporally) dependent is noted. Special analysis issues and problems associated with spatial data are discussed. DSS are defined relative to Sprague's (1980) DSS components model; it is concluded that specialized decision support applications exist for decision aiding but that the model management component for a true DSS is missing. Cross-fertilization from DSS and GIS research is discussed, along with implications for IS management of GIS.