Because most commercially available surfactants consist of mixtures of surfactant components, an understanding of mixed surfactant sorption behavior in the presence of natural materials may be essential for optimal design of surfactant-based industrial processes or environmental remediation applications. This paper demonstrates the application of a new numerical thermodynamic model to the prediction of the mixed sorption behavior of broadly distributed nonionic surfactant mixtures. The model is found to provide excellent agreement with experimental observations for two different ethoxylated nonionic surfactant mixtures, one containing 41 components. In addition, the model is demonstrated to be able to qualitatively and quantitatively duplicate the influence on mixed sorption of variation in sorbent surface area. Procedures for determining model parameters for broadly distributed surfactant mixtures are discussed, and applications for the model are described. Tabulated model parameters that can be used to predict sorption of ethoxylated nonylphenol surfactants to silica are presented. Procedures for applying these parameters to the prediction of the sorption of ethoxylated nonylphenol mixtures on other natural silicate materials are discussed.