Metal-organic framework (MOF) materials are a class of nanoporous materials that have many potential advantages over traditional nanoporous materials for adsorption and other chemical separation technologies. Because of the large number of different MOFs that exist, efforts to predict the performance of MOFs using molecular modeling can potentially play an important role in selecting materials for specific applications. We review the current state-of-the-art in the molecular modeling and quantum mechanical modeling of MOFs. Quantum mechanical calculations have been used to date to examine structural and electronic properties of MOFs and the calculation of MOF-guest interactions. Molecular modeling calculations using empirical classical potential calculations have been used to study pure and mixed fluid adsorption in MOFs. Similar calculations have recently provided initial information about the diffusive transport of adsorbed fluids in MOFs.