Molecular graphics screening of potential zeolite catalysts for the selective synthesis of 2,6-diisopropylnaphthalene indicated that mordenite was a promising candidate. Molecular mechanics calculations of the minimum energy pathway for diffusion of the diisopropylnaphthalene isomers in mordenite showed that significant energy barriers exist for the 2,7 isomer, while the diffusion of the 2,6 isomer is unimpeded. In the case of zeolite L, no significant energy barrier was found for either isomer. In an experimental study of naphthalene isopropylation in a batch autoclave reactor, mordenite produced a 2,6/2,7 ratio of 2.5, while zeolite L was essentially nonselective. The combination of molecular graphics and molecular mechanics appears to be a powerful and reliable method for the screening of zeolites for selective catalysis.