The living anionic polymerization of 4-vinylpyridine (4VP) in 9/1 pyridine/THF at 0 degrees C has been reported lately (Creutz, S.; Teyssie, Ph.; Jerome, R. Macromolecules 1997, 30, 1). The success of its block copolymerization with tert-butyl methacrylate (tBMA) has been shown to be dependent on the addition mode, highlighting the difference in reactivity between the two monomers. Moreover, the (co)solvent also strongly influences the fate of that copolymerization. Thus, the impact of various (co)solvents and additives has been investigated more thoroughly, revealing the interesting possibility of modifying the apparent relative reactivities of these two monomers.