The polymerization of 4-vinylpyridine was conducted in the presence of a cyclic trithiocarbonate (4,7-diphenyl-[1,3]dithiepane-2-thione) as a reversible addition-fragmentation transfer (RAFT) polymerization agent, and a multiblock polymer with narrow-polydispersity blocks was prepared. Two kinds of multiblock copolymers of styrene and 4-vinylpyridine, that is, (ABA)(n) multi-triblock copolymers with polystyrene or poly(4-vinylpyridine) as the outer blocks, were prepared with multiblock polystyrene or poly(4-vinylpyridine) as a macro-RAFT agent, respectively. GPC data for the original polymers and polymers cleaved by amine demonstrated the successful synthesis of amphiphilic multiblock copolymers of styrene and 4-vinylpyridine via two-step polymerization. (c) 2007 Wiley Periodicals, Inc.