The interaction of a water molecule with Si, Si-2, and Si-7 clusters is studied using local-spin-density (LSD) functional theory, with and without exchange-correlation gradient corrections. Water binds to a Si atom in a triplet state, with st binding energy of 0.704 eV, while it does not bind stably to Sia, forming a metastable singlet state Si-Si-OH2 cluster, whose dissociation into Si-2 + H2O involves a barrier. Water binds weakly to Si-7. Binding in the ionized species is much stronger. in all cases binding is through formation of a Si-O bond, with a partial donation of charge from the oxygen, accompanied by the development of a large dipole moment.