An investigation of nocturnal slope winds was conducted on the gently sloping floor of the Salt Lake Valley southwest of Salt Lake City, Utah, at the foot of the Oquirrh Mountains in October 2000 as part of the Vertical Transport and Mixing Experiment (VTMX). The experiments investigated the temporal and spatial development of the vertical structure of the slope flow along a line of four tethered balloons running down the 1.58 degree slope. Supplementary data were also collected from a minisodar, a scintillometer, a 3-D sonic anemometer, and standard weather stations. The slope flow depth reached 100 m AGL and the strength reached 5-6 m/s at the 15-m height of the jet maximum. The downslope flow was strongly affected by the larger-scale flows within the valley above the slope, often producing a strong directional shear above the jet axis. The temperature deficit over the slope reached 7 deg C in 25 m. The slope flows, while well-developed in the early evening, often became weak and intermittent in the middle of the night as a valley inversion built up to the altitude of the slope flow investigation site. The paper will introduce the experimental design and present initial analyses.