We have determined the crystal structures of regioregular HH-TT oligomers with a variety of side chains, including hydroxy-bearing side chains capable of H-bonding. The H-bonding orders the molecular packing into infinite 2-D sheets of Φ-stacks. In these H-bonded sheets, the Φ-stacks are insulated from each other by the aliphatic side chains and form one-dimensional “wires”. In contrast, the structures of similar oligomers that do not have H-bonded side-chains feature a structure in which neighboring Φ-stacks in are in contact (“shorted wires”). The effects of these differing molecular arrangements on the spectral properties and exciton splitting are discussed.