Phosphorus-containing alternating copolymers were synthesized by the reaction of nucleophilic monomers MN with electrophilic monomers ME. Methyl acrylate and γ-butyrolactone were used as ME monomers, with 2-(4-methylphenyl)-1,3,2-dioxaphospholane and 2-(4-methylphenyl)-4-methyl-1,3,2-dioxaphospholane as MN monomers. The polymerizations proceeded without catalyst to give true alternating copolymers which were characterized by spectral and other methods. © 1988.