A detailed comparison is made of several local-composition lattice models. The models considered include several popular activity coefficient models : the Wilson equation, Guggenheim＇s quasichemical theory (GQC), the nonrandom two-liquid theory (NRTL), and the universal quasichemical (UNIQUAC) theory. Also considered are three recently developed lattice models : the Born-Green-Yvon (BGY) model, the nonrandom surface fraction (NRSF) model, and the Aranovich-Donohue (AD) model. Similarities and differences in the assumptions regarding the local compositions are examined. Detailed comparisons are made for both symmetric and asymmetric monomer mixtures as well as for polymer/solvent mixtures with Monte Carlo simulations.