The structure and binding energies are determined for many of the M(H₂O)⁺_n and M(H₂O)²⁺_n species, for n=1–3 and M=Mg, Ca, or Sr. The trends are explained in terms of metal sp or sdσ hybridization and core polarization. The M(NH₃)⁺_n systems, with M=Mg or Sr, are also studied. For the positive ions, the low‐lying excited states are also studied and compared with experiment. The calculations suggest an alternative interpretation of the SrNH⁺₃ spectrum.