Differential vapor pressures were measured for the mixtures of two linear methylene ester oligomers in p-dioxane and chloroform at (25, 30, 35, and 40) degrees C, at various concentrations. The Flory-Huggins interaction parameter chi as well as its enthalpic component kappa were calculated. Large differences in interactive magnitudes between the two solvents in a given oligomer as well as between the two oligomers in a given solvent were observed.