This volume represents the proceedings of the International Symposium on Gravity, Geoid, and Space Missions (GGSM2004), held in Porto, Portugal, 30 August - 3 September 2004. The symposium encompassed the themes of Commission 2 (Gravity Field) of IAG, as well as interdisciplinary topics related to geoid and gravity field, including integration of heterogeneous data and contributions from satellite and airborne techniques. Special focus was on gravity-dedicated satellite missions like CHAMP, GRACE, and GOCE. Projects addressing topographic and ice field mapping using SAR, LIDAR, and laser altimetry, as well as missions and studies related to planetary geodesy were also covered.