Water for production of agricultural crops is becoming increasingly limited in semiarid South Texas. Irrigation scheduling must be based on knowledge of crop water use in order to maximize production with the available water. Evapotranspiration is the accepted standard for determining crop water use based on climatic conditons; but must be calibrated regionally for soil and crop by developing crop coefficient curves. The objective of this study was to estimate sugarcane daily evapotranspiration (ETc) from changes in soil water content and to calculate sugarcane crop coefficients from ETc and reference evapotranspiration (ETo). Among the various methods available to measure soil moisture, capacitance probes attached to data loggers has proven to be effective at determining changes in volumetric water content. Water loss from the soil early in the growing season was primarily a result of surface evaporation. Crop stress limited evapotranspiration as soil moisture levels declined. Crop coefficients developed based on soil moisture depletion determined in this study showed good agreement with published values from the United Nations FAO.