The ground-based soil moisture data collection activities in support of SGP97 will result in perhaps the most comprehensive data set available for validating remote sensing inversion algorithms and studies of large-area soil moisture variability. Within the 50 km by 250 km SGP region, soil moisture content was monitored on a near daily basis over a 1-month period, on a variety of spatial scales and over a range of depths into the soil profile. Monitoring activities fell into three categories: gravimetric moisture content sampling, impedance probe sampling, and soil profile moisture content monitoring. Gravimetric moisture content sampling formed the backbone of the SGP97 ground truth effort and was conducted at nearly 50 sites across the SGP study area. Impedance probe sampling was conducted at 12 selected sites in order to more accurately quantify variability in surface moisture content within ESTAR remote sensing footprints. Moisture content variations within the soil profile were monitored at several locations in order to better understand issues of spatial variability, the relationship between surface moisture content and that at depth, and further, to explore the feasibility of using sparse soil moisture monitoring networks like the Oklahoma Mesonet for ground-truthing larger-footprint soil moisture remote sensing associated with potential future global satellite missions. The purpose of this presentation is to provide an overview of the different data types collected and of several ongoing research activities that are utilizing these data