We developed an algorithm to estimate surface soil moisture, vegetation optical depth and fractional open water cover using satellite microwave radiometry. Soil moisture results compare favorably with a simple antecedent site precipitation index, and respond rapidly to precipitation events indicated by TRMM. High optical depth reduces soil moisture sensitivity in forests and croplands during peak biomass, although tundra locations maintain soil moisture sensitivity despite high optical depth. Optical depth varies with characteristic seasonality across vegetation cover types and tracks measures of vegetation canopy cover from MODIS. The algorithm developed in this study is able to monitor the daily variability of several important land surface state variables.