The Illinois State Geological Survey (ISGS) maintains an on-line clearinghouse for digital spatial data and imagery. The Illinois Natural Resources Geospatial Data Clearinghouse (Illinois Clearinghouse) is an Internet catalog or “store” of free, downloadable, geographically referenced digital data and imagery for Illinois. The project is associated with the Federal Geographic Data Committee's (FGDC) National Spatial Data Infrastructure (NSDI) clearinghouse. The data served are applicable to a wide range of natural resource issues, including geologic mapping, water quality and availability, soil conservation, mineral resource availability, and land cover analysis. Available data sets and documentation (metadata) include: Digital Raster Graphics (DRG) files of topographic maps, 1998/1999 digital orthophoto quarter-quadrangles (DOQs), geology, water resources, nature preserves, wildlife areas, land cover, political boundaries, roads, census information, and the Public Land Survey grid. The Illinois Clearinghouse offers an accessible, external view of a significant portion of the total ISGS database. We plan to make additional databases e.g., detailed geologic maps, available as they are developed. We view the Illinois Clearinghouse as a vital service to the mapping community in Illinois. The Illinois Clearinghouse can be accessed on-line at http://www.isgs.uiuc.edu/nsdihome/.