PURPOSE: To provide a polymn. process for producing a polymer with a narrow mol.wt. distribution.

CONSTITUTION: This process comprises the addition of a monomer and an initiator to a reaction vessel using a monomer feed profile and an initiator feed profile wherein the feed profiles are such that the ratio of monomer concn. to initiator concn. is determined in accordance with a polymn. kinetics relationship between a selected degree of polymn. and monomer concn., initiator concn., reaction temp., and a polymn. efficiency factor to obtain an approximately constant degree of polymn. for a polymer produced during the polymn. process. The polymn. efficiency factor accounts for deviations from ideal kinetics relationships. This process can be used in a semibatch or semicontinuous type for producing a polymer, esp. an acrylate of methacrylate polymer, with a narrow mol.wt. distribution.