We have conducted a first principles density functional theory (DFT) calculation to explore the electronic structure of sodalite at various stages of Al-substitution. By calculating the electronic structure of both substituted and unsubstituted frameworks, with and without the presence of extra-framework atoms, we show that Al-substitution and cation compensation essentially affect the electronic structure only at the upper valence band edge (i.e., the frontier orbitals of reactivity theory). In addition, we show that the equilibrium positions of the extra-framework cations are located in the vicinity of the frontier orbitals which are preferentially localized near aluminum.