Nine disilenes have been studied by solid-state NMR spectroscopy, under static or slow magic-angle spinning conditions, to determine the Si-29 chemical shift tensors. All of the compounds show strong deshielding along one axis and correspondingly large spreads of the tensor components, Delta delta (=delta(11) -delta(33)) MO calculations on model disilenes indicate that the deshielding results from a paramagnetic contribution along the in-plane axis perpendicular to the Si-Si vector. Implications of the NMR data and the theoretical camputations for Si=Si bonding are discussed.