A vinylphosphonate monomer, dimethyl vinylphosphonate (DMVP), has been polymerized by anionic initiators. Anionic polymerization of DMVP with tert-butyllithium (t-BuLi) in combination with a Lewis acid, tributylaluminum (n-Bu3Al), in toluene proceeded smoothly to give an isotactic-rich poly(dimethyl vinylphosphonate) (PDMVP) with relatively narrow molecular weight distribution. Although all the PDMVPs were soluble in water, the isotactic-rich PDMVP was insoluble in acetone and in chloroform which are good solvents for an atactic PDMVP prepared by radical polymerization. The isotactic-rich PDMVP showed higher thermal property than that of the atactic PDMVP. Moreover, we successfully prepared poly(vinylphosphonic acid) (PVPA) through the hydrolysis of the isotactic-rich PDMVP, which formed a highly transparent, self-standing film. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1677-1682, 2010