A well-defined triblock copolymer is synthesized by using a strategy in which the alpha-coupling of 11 thiophene rings of the middle block and the monodispersity (DP = 30 and (M) over bar(w)/(M) over bar(n), = 1.1) of the two polystyrene outer blocks is ensured. Monofunctional polystyrene 1 is first modified with an alpha-terthiophene unit 2 to form 3, and two of these units are coupled in a double Stetter reaction of 4 with a difunctional alpha-terthiophene 5 to yield a tetraketone 6 as the precursor of the triblock copolymer, which was formed with excess Lawesson＇s reagent. The polymer 7 is fully characterized with IR and NMR spectroscopy and MALDI-TOF mass spectrometry. Size exclusion chromatography, transmission electron microscopy, and scanning force microscopy show that 7 is self-assembled into spherical, micellar structures with average diameters of 12 nm, which corresponds to about 60 block copolymer molecules per aggregate. The optical properties of 7 are in full agreement with an associated unsubstituted oligothiophene. Electrochemical doping is hampered by the polystyrene shell; however, chemical doping afforded small nanoscopic charged aggregates that are soluble in organic solvents.