The ESA explorer core mission GOCE, to be launched in 2006, will enhance our knowledge of the global static gravity field and of the geoid by orders of magnitude. The U.S. satellite gravity mission GRACE (2002-2006) is currently measuring, in addition, the temporal variations of the gravity field. With these new data a whole range of fascinating new possibilities will be opened for solid Earth physics, oceanography, geodesy and sea-level research. The new generation of gravity missions employs sensor concepts for gravity field measurement, orbit and attitude control and orbit determination that show interesting similarities with space experiments planned in the field of fundamental physics. This volume is the result of a workshop that brought together some 50 acknowledged experts in their field to discuss (1) strategies for ultra precision orbit determination and gravity field modelling with the data of the upcoming gravity field missions, (2) the use of accurate and high resolution gravity models in Earth sciences whereby, in particular, synergy is expected between the various science fields in their use of this type of new information, and (3) gravity field requirements and possible sensor and mission concepts for the time after GRACE and GOCE.