Molecular mechanics calculations were employed to study the inclusion of 2-methyl naphthoate in alpha- and beta-cyclodextrin in vacuo and in the presence of water as a solvent. The driving forces for complexation are dominated by nonbonded van der Waals host:guest interactions in both environments. The 2-methyl naphthoate penetrates completely into the cavity of beta-cyclodextrin, but there is only partial penetration by the same molecule into the smaller cavity of alpha-cyclodextrin.