The poly(phenylenevinylene) skeleton was selected as a magnetic coupler of polyradicals, because of its developed pi-conjugation, coplanarity, and solvent-solubility even after substitution on the phenylene ring. By synthesizing poly(1,4- or 1,2-phenylenevinylene)-2- or -4-substituted with a stable phenoxy or nitroxy radical, an intramolecular, through-bond and long-range, but strong, ferromagnetic exchange interaction was realized for the first time. The polyradicals were chemically stable and, even at their spin concentration of ca. 0.5, displayed (S) over bar values of 2/2 similar to 4/2.