In summary, we report that a Pd6L4 coordination cage assembled from a triimidazole ligand and a cis-blocked Pd 2+ complex can exist as two isomers, T and C, which can be interconverted in a quantitative yield. The interconversion is induced by guests whose shape matches that of T's or C's cavity. We found that the T⇄C equilibrium can also be shifted in situ using encapsulated azobenzenes, whose photoisomerization is accompanied by a significant change in molecular shape. The next steps will focus on investigating whether reversible toggling between architecturally different cages can translate into reversible switching of function, such as catalysis and modulation of photophysical properties of encapsulated fluorophores. We also aim to assess the generality of our findings by working with cages assembled from ligands in which the central six-membered ring is 1,3,5trisubstituted with heterocyclic rings other than imidazole (e.g., pyrazole, oxazole, and thiazole) and investigating how different guests identified here navigate the thermodynamic landscape of such cages. These studies will then be extended to cages assembled from lower-symmetry ligands, such as 1-pyridyl-3,5-diimidazolylbenzene.