A series of experiments has been conducted during the last decade to develop a radio interferometry system capable of measuring crustal and rotational motions of the earth, as well as source positions for a reference frame based on compact extragalactic radio sources. With the exception of one session between Big Pine, California, Westford, Massachusetts, the observing stations have been those of NASA's Deep Space Network in California, Spain, and Australia. Approximately 2400 observations of extragalactic radio sources were made between August 1971 and February 1980 during 48 separate sessions. A single multiparamter fit was applied to the observed values of delay an delay rate to extract astrometric and geophysical parameters from this decade-long sequence. The fit produced estimates of 684 parameters, including station locations, radio source positions, polar motion, universal time, the precession constant, and solid earth tides. the a priori model included gravitational bending, the 1980 International Astronomical Union (IAU) nutation series, the 1976 IAU expressions for Greenwich mean sidereal time and precession, Bureau International de l'Heure estimates of universal time and polar motion, and monthly mean values for zenith troposphere delay. The rms residuals were 0.52 ns for delay and 0.30 ps/s for delay rate. Intercontinental baseline lengths have been determined with formal uncertainties (for the more recent data) of 0.5 ms for UT1 and 6 and 2 milliseconds of arc (mas), respectively, for the X and Y components of polar motion. Our 1971-1980 data produced an estimate of the lunisolar precession constant that is smaller than the 1976 IAU value by 3.8 mas/yr with an approximate accuracy (1&sgr;) of 2 mas/yr. The earth tide results agree with the commonly accepted values.