text: A significant second-order effect on the Perturbation Molecular Orbital model of homoaromaticity is the addition of a second homoconjugate linkage and its influence on stability. The effect is often a doubling of the instability brought about by the addition of a single homoconjugate linkage, although there is an additional term that depends on the proximity of the two linkages. In order to minimize δβ and thus keep the coupling term to a minimum, bishomoaromatic compounds form depending on the conformation of greatest stability by resonance and smallest steric hindrance. The synthesis of the 1,3-bishomotropenylium cation by protonating cis-bicyclo[6.1.0]nona-2,4,6-triene agrees with theoretical calculations and maximizes stability by forming the two methylene bridges at the 1st and 3rd carbons.