The restrictions on the configurations available to the cross-link junctions of a network, arising from its presence in a dense phase, have a well-established effect on the mechanical properties of elastomers. These constraints give rise to intermolecular cooperativity of the junction motions and hence can be well described by models of constraint dynamics in relaxation phenomena. This connection between junction dynamics and elasticity of networks is illustrated by comparing the predictions of the coupling model of relaxation with the constrained junction model of Flory. The comparison is borne out by recent P-31 NMR results on networks.