The formation of a nanostructured interpenetrating polymer network (IPN) via electropolymerization is described. The electro-copolymerization of alternate layer-by-layer (LbL) self-assembled polyelectrolytes with thiophene and carbazole pendant monomers was demonstrated facilitating IPN formation of π-conjugated polymers or conjugated polymer network (CPN) films. UV-Vis spectroscopy, QCM, and ellipsometry confirmed linear nanostructured LbL film growth. Electrochemical crosslinking by cyclic voltammetry (CV) manifested highly regular peak current increases with successive cycles. A quantitative correlation of the LbL layer number with the cathodic charge and scan rate was observed. Electrochemical impedance analysis confirmed CPN film formation and the change in capacitance behavior. The electropolymerization of a nanostructured layer-by-layer (LbL) film enables interpenetrating polymer network (IPN) formation in a very quantitative manner. Oppositely charged polyelectrolyte precursors facilitate formation of IPN of π-conjugated polymers or simply conjugated polymer network (CPN) films by electropolymerization. UV-Vis absorption spectroscopy, QCM, ellipsometry, EIS, and AFM are used to characterize the films. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.