The first geodetic survey across the northern Caribbean plate boundary zone with the Global Positioning System (GPS) was conducted in June 1986. Baseline vectors defined by the six station regional GPS network ranged from 170 to 1260 km in length. Repeatability of independent daily baseline estimates was better than 8 mm plus 1.3 parts in 108 of baseline length for horizontal components. The wet tropospheric path delay during the experiment was both high, sometimes exceeding 30 cm at zenith, and variable, sometimes exceeding 5 cm variation over several hours. Successful carrier phase cycle ambiguity resolution (“bias fixing”) could not be achieved prior to construction of a regional troposphere model. Tropospheric calibration was achieved with water vapor radiometers at selected sites, and with stochastic troposphere models and estimation techniques at remaining sites. With optimum troposphere treatment and single-day orbital arcs, we resolved most biases on baselines up to about 550 km in length. With multiday orbital arcs we resolved most biases in the network regardless of baseline length. Our results suggest that constraints on plate boundary zone deformation in the Greater Antilles, and on the North America-Caribbean relative plate motion vector, can be obtained with a series of GPS experiments spanning less than 10 and 15 years, respectively.