A refinement has been obtained in the earth's gravitational field by using satellite and surface data. In addition to a more complete treatment of data previously employed on 27 satellites, the new satellite solution Gem (Goddard Earth Model 7) includes 64,000 laser measurements taken on seven satellites during the International Satellite Geodesy Experiment program. Gem 7, containing 400 harmonic terms, is complete through degree and order 16. The companion solution Gem 8 combines the same satellite data as Gem 7 with surface gravimetry over 39% of the earth. Gem 8 is complete to degree and order 25. Extensive tests on data independent of the solution show that the undulations of the geoidal surface computed by Gem 7 have an accuracy (for commission errors only) of about 2-1/2 m (rms). The overall accuracy of the geoid calculated by Gem 8 (including short-wavelength components not in the solution) is estimated to be about 4 m (rms), an improvement of almost 1 m over previous solutions. The new combination solution is the first to show signs of 'convection rolls' in the upper mantle below the Pacific Ocean.