A prior correlation model for glass formation based on cluster-size distribution kinetics is here applied to mixtures of glass-forming compounds. The model was developed to describe the dielectric relaxation or viscosity response to temperature and pressure of pure compounds, and has successfully been extended to binary mixtures of glassformers that exhibit a single relaxation versus temperature. The model describes how rapid cooling or compressing a liquid mixture leads to structural arrest and a consequent sharp rise in viscosity or dielectric relaxation time. The approach leads to scaled pressure and temperature correlations and plots for viscosity that reveal strong and fragile glass behavior, and agree with experimental data. Recent work has extended the model to binary mixtures of glassforming compounds exhibiting two relaxations versus temperature. In order to do so, the model parameters are first determined for the pure components, and these are then used to describe mixture relaxation behavior. With these parameters, the dielectric relaxation or viscosity can be calculated at various temperatures and pressures.