We have investigated the effects of relativity on the atomization energy of silane, SiH4, to attempt to resolve an earlier discrepancy between theory and experiment. Using a spin-free no-pair Hamiltonian that is based on a second-order Douglas-Kroll transformation, we find that relativity reduces the atomization energy of SiH4 by 0.7 kcal mol(-1) : a small change, but sufficient to bring theory and experiment into agreement when we include experimental uncertainties. Excitation energies in the silicon atom, S-5(sp(3))-P-3(s(2)p(2)), and the atomic cation, P-4(sp(2))-P-2(s(2)p), which involve a reduction in the number of s-electrons, increase similar to 1.2 kcal mol(-1) when we include relativity. These excitation energies show an even larger increase, about 2.5 kcal mol(-1), when we include con correlation. By contrast, the ionization potential, which involves no change in the number of s-electrons-electron configurations s(2)p(2) in the neutral atom and s(2)p in the cation-changes similar to 0.2 kcal mol(-1) when we include relativity. These predictions are consistent with the notion that s-electrons are the most affected by relativity, and that changes in the amount of s-character are related, qualitatively, to differential relativistic effects.