The effect of polarization on the phase behavior of binary fluid mixtures has been investigated using grand canonical Monte Carlo ( GCMC) simulations with histogram reweighting. The adiabatic nuclear and electronic sampling ( ANES) algorithm of Chen and Siepmann ( Theor. Chem. Acc. 1999, 103, 87) is used to incorporate polarization into the simulations. We apply the ANES algorithm to mixtures of Stockmayer and polarizable Lennard-Jones ( LJ) fluids, including two model colloidal systems and a mixture of methanol and methane at 330 K. It is found that the critical point ( temperature, composition, and pressure) of the mixture decreases with increasing polarizability. Significant deviations from the nonpolarizable fluid system are also seen in the liquid-phase behavior of the phase diagram. Incoporation of polarization into a methanol-methane mixture more accurately reproduces the experimental results.