Three block copolymers, P3AT(S*)-b-P3AOT, P3AT(R*)-b-P3AOT(S*), and P3AT(S*)-b-P3AOT(S*), composed of an alkyl- and an alkoxy-substituted poly(thiophene) block, were synthesized using the living chain-growth polymerization of poly(3-alkylthiophene)s. One or both of the blocks are equipped with a chiral side chain. The formation of the block copolymers was confirmed by GPC and H-1 NMR experiments. UV-vis, circular dichroism, and emission spectroscopy were used to study the conformational and supramolecular behavior of these block copolymers in solution. This revealed that the block aggregating first upon addition of nonsolvent has a major influence on the stacking and the chiroptical behavior of the other block.