UNAVCO Community GPS Seamless Archive (GSAC) Project C. Meertens, F. Boler, and L. Estey, (chuckm@unavco.ucar.edu, 303-497-8011; fboler@unavco.ucar.edu and lou@unavco.ucar.edu) all at: UNAVCO/UCAR Box 3000, Boulder, CO 80307 USA M. Scharber (mscharber@josh.ucsd.edu) Scripps Inst. of Oceanography La Jolla, CA 92037 USA UNAVCO and other members of the GPS community have been engaged for several years in the development of a seamless archive that permits the simple accessing of data from many, diverse, international GPS data archive centers. The ultimate goal is to allow GPS data users to browse the web site of any GSAC participant and view and retrieve the data holdings of all participants. The basic tables describing individual archive data holdings have been defined and are available at several archives. GSAC interface and retrieval tools are under development. Possible future extensions to the GSAC concept include tables and tools for data flow monitoring, synchronization of data holdings, and descriptions of GPS analysis and modeling product holdings.