A computationally simple and accurate model is presented for predicting partial structure factors of binary mixtures of electrostatically stabilized colloidal particles. The theory is based on the mean spherical approximation of a binary mixture of hard sphere fluids interacting with a screened Coulomb (Yukawa) potential and a rescaling of the hard sphere sizes of the components. The utility of the approach is tested against data from small-angle neutron scattering experiments and Monte Carlo simulations.