The synthesis, isolation, and characterization are reported of a polystyrene-poly(2-vinylpyridine) block copolymer "catenane" with a molecular weight of about 10 000 and containing about equal masses of each of the rings. This catenane is prepared by end-to-end coupling of a P2VP dianion lithium salt with 1,4-bis(bromomethylbenzene) in THF in the presence of a PS macrocycle.(M-p = 4500). The catenane was isolated by precipitation-extraction procedures that were optimized using a 50/50 PS-b-P2VP macrocycle as a model for the catenane. The catenane copolymer was characterized by SEC, H-1 NMR, and emission (fluorescence) spectroscopy.