This paper presents the problems and results of building a biological inventory GIS for Hawk Mountain Sanctuary, Berks County, Pennsylvania. Hawk Mountain Sanctuary is dedicated to preserving the habitat of one of the major flyways for raptors in the northeastern United States. The basic purposes of the GIS are to identify habitats, determine available resources, and identify areas of potential expansion of sanctuary control. Since the sanctuary spans several political jurisdictions, the process of developing the GIS had to overcome a number of problems, which are the focus of this report.