The coordination behavior of the calixarene-based N₄O₄ donor ligand H₆L bearing two pendant 8-hydroxyquinoline-2-hydrazone arms towards the lanthanide ions Tb³⁺, Dy³⁺, and Yb³⁺ has been investigated. H₆L was found to support tetra- and dinuclear mixed-ligand complexes with the pendant hydrazone units in a deprotonated enolate and/or a neutral amide form. The direct reaction of H₆L with Ln(NO₃)₃(H₂O)₆ and NEt₃ in a 1:1:2 molar ratio leads to tetranuclear [Ln₄(H₃L)₂(µ-OH)₂(η²-NO₃)₄] complexes {Ln = Tb (1), Dy (2), Yb (3)} containing a rectangular arrangement of four eight-coordinate Ln³⁺ ions bridged by two hydroxido- and four quinolinolato-O atoms as established by X-ray crystallography. Degradation of 2 occurs upon addition of further equiv. of H₆L to give dinuclear [Dy₂(H₄L)(NO₃)₂(MeCN)₂]NO₃ (4) with eight- and ten-coordinated Dy³⁺ ions. ESI-MS studies reveal that such dinuclear species exist also in the solution state. The results of variable temperature direct and alternating current magnetic susceptibility measurements for 1–4 and high frequency EPR study on 4 are also reported.