Isotactic poly(beta-methyl-beta-propiolactone) (poly(CH3-PL)) and poly(beta-ethyl-beta-propiolactone) (poly(C2H5-PL)) with (S) and (R) configurations, respectively, were synthesized in yields of 70% via the polymerization of optically active beta-(trichloromethyl)-beta-propiolactone (CCl3-PL) and beta-(dichloroethyl)-beta-propiolactone (CH3CCl2-PL). The polymerization was conducted in bulk, under vacuum, using the triethylaluminum/water or the diethylzinc/water catalysts. These polymerizations were followed by the dechlorination of the resulting chlorinated polymers, using the tri-n-butyltin hydride (Bu3SnH) reducing agent. C-13 NMR spectroscopy shows that all the chlorinated and dechlorinated polymers have a degree of isotacticity of 100%, indicating that little or no racemization occurs during the course of the polymerization. Atactic homologues were also synthesized; these are soluble in the usual organic solvents, contrary to the isotactic polymers. Multiangle laser light scattering analyses of atactic polymers indicate that the dechlorination reaction occurs with some degradation, leading to poly(CCl3-PL) and poly(CH2CCl2-PL) with molecular weights of about 5000. The variations of the glass transition temperature, melting temperature, and enthalpy of fusion with the dechlorination ratio are discussed. The whole analysis shows that the dechlorination reaction generates statistical copolymers, with the formation of the intermediate homopolymers poly(CHCl2-PL) and poly(CH2Cl-PL) in the case of the dechlorination of poly(CCl3-PL). X-ray patterns show that each homopolymer has its own crystalline structure and that the semicrystalline copolymers adopt a crystalline structure similar to that of the homopolymer of closest composition.