We report preliminary results of ab initio calculations on (NaCl)(n), (MgO)(n), and (CaO)(n) clusters for n=1-6. We determine the isomers and the structure of various neutral clusters. Their relative stabilities are studied by analyzing their binding energies and their dissociation energies. As a particular behavior of (MgO)(n) is observed for n=3 and n=6, the bondings of (MgO)(3), (CaO)(3), and (NaCl)(3) are studied.