The elastic contribution (µ1 k- µ10)el to the chemical potential of the diluent in a swollen network is treated according to recent theory which takes account of constraints on junctions in real networks. The quantity λ(µ1 - µ10)el) a, where λ is the linear expansion ratio, exhibits a maximum with increase in λ in qualitative agreement with experimental measurements, but contrary to previous theories. The premise that the free energy of a swollen network is additive in the contributions from mixing and elastic deformation is supported by the comparison of experiment with theory. © 1979, American Chemical Society. All rights reserved.