The satellite to satellite tracking (SST) technique has been used to measure the earth's gravity field. Data from the Apollo/Soyuz and GEOS 3 missions, obtained at greatly differing altitudes, have been used in combination to determine 5¿ and 10¿ equal area mean gravity anomalies in the South Atlantic and Indian Ocean and over the African continent. The Apollo/ATS 6 SST data consist of 47 passes of data taken from the 230-km Apollo altitude, while the GEOS 3/ATS 6 data set consists of 45 passes taken from 840-km altitude. Through a combination of the two data sets with the GEOS 3 SST data providing stability for the solution at the longer wavelengths, excellent (5¿ at ¿3 mgal, 10¿¿1 mgal) results were obtained for this largely unsurveyed region. These results have been compared to an altimetric surface at comparable wavelengths, providing good agreement (¿1 mgal for 10¿ blocks and ¿5 mgal for 5¿ blocks) between these independent measuring techniques. The terrestrial data over the African continent is shown to differ significantly (rms difference of 8 mgals with a maximum difference of 23 mgals) from a comparison of 10¿ GEOS 3 SST derived blocks. A simulation has also been performed to assess the data requirements, aliasing, and noise characteristics of a low spacecraft being tracked in a high-low SST configuration. The results of the simulation were employed in the design of the SST data reduction procedures.