We consider the possible quantitative application of a lattice-gas model approach to the calculation of adsorption isotherms. In order to validate such application, we use the lattice-gas approach to solve for the adsorption and desorption isotherms in model controlled-pore glasses that have previously been the subject of an extensive series of Grand Canonical Monte Carlo simulations. We find that the lattice-gas model augmented with longer-ranged interactions provides a quite good account of adsorption in some of these systems for appropriate choice of several system parameters, but that the quality of agreement depends on the pore size of the material.