The tetradentate imino-carboxylate ligand L2- chelates the equatorial sites of NiII to give the complex Ni(L)(MeOH)2 in which a NiII center is bound in an octahedral coordination environment with MeOH ligands occupying the axial sites. Lanthanide (Ln) and Group II metal ions (M) template the aggregation of six Ni(L) fragments into the octahedral cage aggregates {MNi(L)6} x + (1:  M = SrII; x = 2, 2:  M = BaII; x = 2, 3:  M = LaIII; x = 3, 4:  M = CeIII; x = 3, 5:  M = PrIII; x = 3, and 6:  M = NdIII; x = 3). In the presence of Group I cations, however, aggregates composed of the alkali metal-oxide cations template various cage compounds. Thus, Na+ forms the trigonal bipyramidal Na5O3+ core within a tricapped trigonal prismatic Ni(L)9 aggregate to give {(Na5O)⊂Ni(L)9(MeOH)3}(BF4)2·OH·CH3OH, 7. Li+ and Na+ together form a mixed Li+/Na+ core comprising distorted trigonal bipyramidal Na3Li2O3+ within an approximately anti-square prismatic Ni(L)8 cage in {(Na3Li2O)⊂Ni(L)8(CH3OH)1.3(BF4)0.7}(BF4)2.3·(CH3OH)2.75·(C4H10O)0.5, 8, while in the presence of Li+, a tetrahedral Li4O2+ core within a hexanuclear open cage Ni(L)6 in {(Li4O)⊂Ni(L)6(CH3OH)3}2ClO4·1.85CH3OH, 9, is produced. In the presence of H2O, the Cs+ cation induces the aggregation of the Ni(L)(H2O)2 monomer to give the cluster Cs2Ni(L)(H2O)26·2I·4CH3OH·5.25H2O, 10. Analysis by electronic spectroscopy and mass spectrometry indicates that in solution the trend in stability follows the order 1−6 > 7 > 8 ∼ 9. Magnetic susceptibility data indicate that there is net antiferromagnetic exchange between magnetic centers within the cages.