Atom transfer radical polymerization (ATRP) of dimethyl(l-ethoxycarbonyl)vinyl phosphate (DECVP) was investigated in the presence of different catalyst systems and initiators. Polymers with controlled molecular weight and relatively low polydispersity (PDI < 1.5) were obtained through ATRP initiated with ethyl 2-bromoisobutyrate (EBriBu) in the presence of Cu(I)Cl/2,2'-bipyridine (bpy). Faster polymerization and higher monomer conversion were obtained in the polymerization using Cu(I)Cl/ N,N,N',N '',N ''-pentamethyldiethylenetriamine (PMDETA) or Cu(I)Cl/1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) as the catalyst system. PDECVP dissolves in water below 70 degrees C, but its lower critical solution temperature (LCST) depends on the polymer concentration. The conversion of PDECVP to poly((l-ethoxycarbonyl)vinylphosphonic diacid) (PECVPD) was accomplished by reaction with bromotrimethylsilane followed by methanolysis. Block copolymers, PDECVP-b-poly(styrene) (PS), PDECVP-b-PS-b-PDECVP, and PDECVP-b-poly(methyl methaerylate) (PMMA), were synthesized by extending from PS-Br, Br-PS-Br, and PMMA-Br macroinitiators. The controlled block copolymers were obtained, PDECVP-b-PS with M. = 40 500 g/mol and PDI = 1.4, PDECVP-b-PS-b-PDECVP with M-n = 41500 g/mol and PDI = 1.23, and PDECVP-b-PMMA with M. = 29 700 g/mol and PDI = 1.08. Initiation efficiency exceeded 94% using PMD/IA-Br as the macroinitiator.