Space geodesy has evolved in the last twenty years into one of the most exciting disciplines in the earth sciences. This development is due to a large extent to the versatility of applications provided by the radio interferometric technique called Global Positioning System or GPS. Appropriately, Symposium 102: Global Positioning System: An Overview was held at the 125th Anniversary Meeting of the International Association of Geodesy in August, 1989. A broad review of GPS geodesy, achievements to date and the prospects for future study and application was presented. Papers included in this volume are grouped as follows: - Static and Geodynamic Positioning; - Orbit Determination Optimization and Design Dynamic; - Kinematic GPS/INS Radio Tracking Systems A useful reference for any researcher or student of space geodesy.