Polystyrene-block-poly(2-vinyl pyridine)-block-poly(methyl methacrylate) ABC triblock copolymers were synthesized by sequential living anionic polymerization. Their solution properties were investigated in toluene, which is a bad solvent for the middle block. Spherical micelles are formed, which consist of a poly(2-vinyl pyridine) dense core bearing polystyrene and poly(methyl methacrylate) soluble chains ata the corona. These micelles exhibit the architecture of heteroarm star copolymers obtained by "living" polymerization methods. The aggregation numbers strongly depend on the length of the insoluble P2VP middle block, thus remarkable affecting the size of the micelles.