The miscibility of a random copolymer of ethylene and vinyl acetate with three other copolymers based on poly(ethylene glycol), poly(itaconic acid) and a vinyl acetate-fumaric acid ester has been investigated by d.s.c. and X-ray powder diffraction. Melting point depression data could be analysed using the full Nishi-Wang expression but additional entropy contributions to the miscibility were evident in some mixtures. These were attributed to the presence of long hydrocarbon substituents in the copolymers. For mixtures with the poly(ethylene glycol) based copolymer, a large negative value of the interaction parameter was obtained and there was cocrystallization of the ethylene-vinyl acetate copolymer with the docosyl end groups of the poly(ethylene glycol) based copolymer.