Poly(dimethylsiloxane) networks were prepared by cross-linking the polymer both in the undiluted state and in cyclohexane solutions of varying composition. Stress—strain isotherms of these networks in compression in the unswollen state were found to show only small deviations from the form predicted by the statistical theories of rubberlike elasticity. The dependence of these deviations on the variables which characterize the preparation of these networks indicates that they are not due primarily to nonequilibrium effects. The dependence of the stress itself on the volume at which the networks were prepared is in close agreement with the Flory theory of rubberlike elasticity, which contains a volume-dependent contribution to the elastic free energy of a polymer network. Previous experimental results bearing on the existence and magnitude of such a contribution are critically summarized and reevaluated, thereby definitively settling an important controversy in the area of rubberlike elasticity.