Halogen bonding is an attractive force between a halogen atom and an atom containing a lone pair, where the halogen acts as a Lewis Acid. The term “halogen bond” invites comparison to the hydrogen bond. Both are highly directional and of similar strength, but while multiple hydrogen bonds between two discreet species is common, there are only a few cases where this has been observed in halogen bond systems. The molecule donor/acceptor pairs of 1,8-diazanaphthalene/1,8-dihalonaphthalene and 1,8-diazaanthracene/1,8-dihaloanthracene, using the halogens iodine, bromine, and chlorine, were analyzed with Gaussian '03 using DFT with B3LYP method and 6-31G* basis set to determine whether two parallel halogen bonds are likely to form. For the anthracene systems, all three dihalides formed two parallel halogen bonds; however, for the naphthalene systems, only the dichloro derivatives formed parallel halogen bonds, while the dibromo and diiodo derivatives formed only single halogen bonds due to the large steric repulsion between the halides.