Regioregular poly(3-alkylthiophenes) and other polythiophenes can be prepared by living polymerization which have good solubility, processability and environmental stability. The polymerization method can afford regioregular poly(3-alkylthiophenes) in high yields. Kinetic study of polymerization revealed the living character of this process. The molecular weight of poly(3-alkylthiophenes) is a function of the molar ratio of the monomer to nickel initiator, and conducting polymers with relatively narrow molecular weight distribution (PDI<1.5) are now readily available. Sequential monomer addition resulted in new block copolymers containing different poly(3-alkylthiophene) segments, which further confirms the "livingness" of this system. Other synthetic methods can be used as well to conduct living polymerization. Blends and electronic devices can be prepared.