Quantitative analysis of copolymers is described in detail for a series of copolymers of 2-[(phenylamino)carbonyl]oxyethyl methacrylate and 1-methyl-2-phenoxyethyl methacrylate. Particular emphasis is placed on aspects optimising the accuracy of the technique. Thus the irreproducibility resulting from the use of cast films is overcome when using solutions. The criteria of most appropriate solvent are established. Very satisfactory calibration is afforded by blends of the two homopolymers in solution, thus providing an absolute calibration and obviating the use of model compounds or copolymers of known composition.