A combined first principles (both Hartree-Fock and local density functional) and force field study of the preferred conformations and conformational flexibility of the tris(quaternary ammonium) 2,3,4,5,6,7,8,9-octahydro-2,2,5,5,8,8-hexamethyl-1H-benzo[1.2-c:3,4-c’:6-c"]tripyrrolium ’triquat’ cation [(C4H4N(CH3)(2)))(3)](3+) is presented. The potential energy surface of this molecular cation is characterized by two local minima corresponding to C-3r and C-s symmetry, respectively, and a triple transition state with respect to pyrrolium ring inversion with D-3h symmetry. These structures were each successfully located by both first principles and force field methodologies. Although the conformational energy differences obtained by Hartree-Fock and local density functional methods agree well, some variability in the molecular mechanics results for different force fields is found, underlining the need for a careful calibration of force fields against experimental and/or ab initio data. The implications of the calculated energy barriers for ring inversion in the primary application of the triquat cation as a zeolite ZSM-18 templating agent are also discussed.