Anionic polymerization of lauryl methacrylate (LMA) with 1,1-diphenylhexyl lithium in tetrahydrofuran (THF) at −40 °C resulted in a multimodal and broad molecular weight distribution (MWD) with poor initiator efficiency. In the presence of additives such as dilithium salt of triethylene glycol (G3Li2), LiCl, and LiClO4, the polymerization resulted in polymers with a narrow MWD (≤ 1.10). Diblock copolymers of methyl methacrylate (MMA) and LMA were synthesized by anionic polymerization using DPHLi as initiator in THF at −40 °C with the sequential addition of monomers. The molecular weight distribution of the polymers was narrow and without homopolymer contamination when LMA was added to living PMMA chain ends. Diblock copolymers with broad/bimodal MWD were obtained with a reverse-sequence monomer addition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 875–882, 2004