Specifically designed conducting polymers were prepared from monomers that are covalently linked to duplex DNA. These materials combine the self-assembly properties of DNA with those of conducting polymers and may be valuable in the development of self-directing molecular nanowires. Single-strand DNA oligomers having 2,5-bis(2-thienyl)pyrroles (SNS monomers) covalently linked at every other nucleobase along one strand form stable duplexes with their complementary strands. The duplex DNA serves as a scaffold that aligns the SNS monomers within its major groove. The reaction of these SNS-containing duplexes with horseradish peroxidase and H2O2 (an oxidant) results in the conversion of the SNS monomers to a conjoined (covalently linked) polymer having the optical properties of a conducting polymer. Examination of radiolabeled oligomers confirms bond formation between SNS monomers, and that conclusion is supported by AFM images. The conjoined polymers have structures that are determined and controlled by the DNA template.