Communication: Intermolecular interactions caused by substituents, van der Waals interactions, hydrogen bonds, etc. need to be understood if the directed formation of supramolecular structures is to succeed. A study of the influence of intermolecular and substrate-molecule interactions on the epitaxy of monolayers of terminally mono- and disubstituted 3,3-dipentyl-alpha-quinquethiophenes such as that shown in the Figure is presented.