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Microwave Sensing provides a means to nondestructively determine the amount of moisture in materials by sensing the dielectric properties of the material. In this study, dielectric properties of Vidalia onions were analyzed for moisture dependence at 13.36 GHz and 23C for moisture content between 6% and 92%. Dielectric properties were obtained using an open-ended coaxial-line probe connected to a network analyzer. Linear regression models were developed using the dielectric constant, dielectric loss factor, and a density-independent function. Models were evaluated for calibration effectiveness in predicting moisture content using coefficient of determination (R) and standard error of calibration (SEC). In order to validate the models, a standard error of performance (SEP) was calculated from a set of observations that were not used in the calibration. Preliminary results showed use of a density-independent function was more effective in prediction of moisture content then using dielectric properties alone. The measurements and models presented in this paper constitute the foundation for the development of a sensor for determining the degree of curing an onion has undergone.