New chiral, alternating copolymers of 2,5-dialkoxybenzenes and 3,3'-dialkoxy-2,2'-bithiophenes were prepared and their (chir)optical properties were studied. The polymers were prepared by a Stille coupling reaction and show high conjugation lengths in both solution and films. Fluorescence and UV-vis spectroscopy indicate that the polymers are present as rigid, highly conjugated polymer strands in solution. In a nonsolvent mixture, the polymers aggregate and, if chiral substituents are employed, supramolecular chirality is observed. In annealed films, very large Cotton effects are observed.