The purpose of this study is to compare time series of ESTAR-derived surface (0-5 cm) moisture content to those of mean values observed at 12 intensively sampled footprint sites during SGP97. The intensively monitored sites were part of a study of soil moisture variability within ESTAR footprints. At each of these sites, 49 measurements of volumetric moisture content were made with a portable, TDR-like impedance probe. The intensive monitoring effort complemented the core ground truth campaign, which called for a smaller number of samples (9-14) at a larger number of sites (49). Statistical analysis of the intensively monitored sites has shown that for a given level of variance, the larger number of samples leads to a factor of two reduction in the 95% confidence interval about the mean moisture content. Consequently, at these 12 sites, ESTAR performance can be more rigorously evaluated. At each site, time series of volumetric moisture content derived from ESTAR, impedance probe and gravimetric data are compared, with implications for sensor performance over a range of soil and cover types, and wetness and variance conditions