The factors which affect the dielectric response of food materials are examined in an attempt to establish a predictive model and to obtain a more basic understanding of dielectric properties. Detailed dielectric measurements were performed on rehydrated non-fat dry milk using the precision slotted line technique, at temperatures of 25, 35, 45, and 55°C and at frequencies of 300, 1000, and 3000 MHz. Solute-solute and solute-solvent interaction were found to reduce the dielectric loss factors to levels substantially below those predicted by chemical composition alone; therefore, the dielectric loss cannot be predicted from a linear, additive model based on composition. The results of dielectric measurements of solid food products, beef and turkey were reported. Conductivities of beef juice obtained from cooking were measured and the dielectric losses at 5 to 65°C and 300, 915, and 2450 MHz calculated based on the measured conductivities.