Geographic Information Systems (GIS) are used by government, researchers and businesses in a wide range of domains including economic development, environmental management, education, health, human services, infrastructure management, and disaster response. Most experts agree that the most expensive part of a GIS program is the creation of spatial data. Some estimate that as much as 80% of the cost of any application is attributable to the expenses of acquiring and geocoding information (Thapa & Bosler, 1992). Often the information needs of different GIS applications overlap and data created by one organization can be used by others. Data sharing can therefore help reduce costs of GIS application development and yield considerable benefits and efficiencies. To achieve this purpose, the State of New York has implemented a GIS Coordination Program which features an Internet-based GIS Clearinghouse operated by the New York State Library (Dawes & Eglene, 1998). In this program, the Library acts as a critical implementer and value-added facilitator of an important new state information policy that has influence over spatial data development, exchange, and use at all levels of government and in the private and not-for-profit sectors. The Clearinghouse provides the conceptual framework and operational platform for a fully functioning data cooperative which is the heart of the New York State GIS Data Sharing Policy. The library-based clearinghouse has become the essential portal to many newly identified information resources. It organizes the data descriptions, provides a publicly available and easy-to-use means of access, promotes sharing, points the way to education and other services, and generally makes possible the vision of a living data resource.