[en] Three underground field tests were performed in southeastern New Mexico as part of the US Department of Energy's Waste Isolation Pilot Plant (WIPP) Research and Development Program. These tests, one in potash-rich halite and two in relatively pure halite (rock salt), investigated the feasibility of using borehole inclusion stressmeters to measure in situ stress and stress changes in salt. The tests provided a comparison of inclusion stressmeters and demonstrated various qualities of gage response, including time-dependent characteristics, repeatability, and the effects of preload. Three gage types comprising five gages were used: (1) the strain-gaged stressmeter (SGS); (2) two US Bureau of Mines (USBM) hydraulic pressure cells called the borehole pressure cell (BPC) and the cylindrical pressure cell (CPC); and (3) two development pressure cells called the USBMX and the Sandia Pressure Cell (SPC). Gage response has been reasonably consistent. However, further study is required of the correlations between gage types and between gage output and the in situ state of stress. 13 references, 16 figures, 2 tables