Free radical polymerization of glyceryl methacrylate (GMA) has been conducted (i) in bulk, (ii) in moderately concentrated aqueous solution and (iii) in dilute aqueous solution. For (i) and (ii) the resultant poly(glyceryl methacrylate) (PGMA) was either insoluble or only swelled in a wide range of common solvents, whereas for (iii) solubility occurred in three polar liquids of which only one (2-methoxyethanol) was capable of dissolving poly[GMA-co-methyl methacrylate (MMA)] over the whole range of copolymer composition. The gamma-ray initiated copolymerization of GMA with MMA in bulk has been effected to various conversions. On addition of di-isopropyl ether (DPE) the copolymer was isolated, and carefully calibrated Fourier transform infra-red measurements on the resultant solutions of unreacted monomer mixture in DPE afforded the composition of unreacted monomer mixture. This quantity, in conjunction with the initial feed composition and the value of the fractional conversion, was employed to calculate the monomer reactivity ratios by a specially devised non-linear least-squares program using simplex algorithm, yielding r(MMA) = 0.53 and r(GMA) = 1.61.