In industry, the theology of photographic color coupler dispersions is found to alter with temperature during processing and film coating. The reason for the change in the theological properties with temperature is poorly understood. The color coupler dispersion is found to be so complex that the prediction of rheological behavior from first principles is extremely difficult. To understand this behavior, dispersions of polystyrene lattices have been used because of the well-defined, well-characterized, and easy to control properties of these particles. The steady shear viscosity of the model dispersions (polystyrene lattices) has been measured as a function of shear stress, temperature (25-90 degrees C), particle size, and concentrations of gelatin, NaCl, and surfactant. The effect of temperature on the dispersion medium has been found to follow the Arrhenius equation in the temperature ranges 40-90 degrees C. The theological behavior of the latex-gelatin dispersions in this study has been explained in terms of hydrodynamic interactions between particles as well as nonhydrodynamic interactions such as van der Waals, electrostatic, steric, and Brownian forces.