Dielectric spectroscopy was used to study segmental relaxation in a series of poly(vinylethylene) (PVE) networks. Increasing cross-link density is associated with increasing glass transition temperatures (T(g)) and broader segmental relaxation functions. T(g)-scaled Arrhenius plots of the segmental relaxation times indicate that enhanced intermolecular coupling is the primary mechanism for the observed changes. This is in contrast to the effects of blending and crystallization, both of which cause changes to the segmental relaxation spectra similar to that from cross-linking. However, the origin of these changes is quite different.