The integration of global positioning system (GPS) technology in earth observation activities has become a fact of technological life. Not only is georeferencing of remotely sensed imagery greatly facilitated, but ground reference data delineation for classification and accuracy assessment purposes has been precision-enhanced to previously unheard-of levels. However, the acquisition of GPS locational information is sensitive to both instrument specifications and procedural variations. The goal of this study was to compare the efficiency and accuracy of two mapping-grade GPS systems under different data acquisition scenarios. The Trimble Basic Plus and ProXL receivers were tested with their respective base stations in conjunction with a range of receiver data collection time intervals. For each set of operational parameters, precision of the acquired position is represented by the standard deviation, while the root mean square error (RMS) depicts its accuracy. We conclude that, even with the data collection session reduced to one minute, the Trimble ProXL is truly a sub- meter GPS system. In the case of the Trimble Basic Plus, a session of three minutes is recommended to obtain or even slightly exceed an accuracy of 2.5 meters. The easting, northing, and altitude precision ratio obtained during the tests in Indiana, central USA, is of a magnitude of 1.0:1.5:3.0 in both cases. The effect of distance between base station and portable receives and of environmental factors (specifically in the forestry sector) is the subject of continuing research.