Methyl methacrylate hornopolymerization and copolymerization with styrene catalyzed by rare earth coordination catalysts were carried out in ionic liquids for the first time. It was found that the polymerization rate of MMA and molecular weight of PMMA were higher in ionic liquids than in toluene or in bulk under the same conditions. Both random and block copolymers of MMA with St could be prepared in ionic liquids. The copolymers were characterized by GPC, NMR, and IR measurements. Ionic liquids can be recycled and reused.