In molecular perovskites, the use of molecular ions as building units introduces new chemical and structural degrees of freedom that can couple to external stimuli, producing phenomena such as temperature and pressure-driven A-site order-disorder phase transitions, unconventional octahedral tilts and shifts that can couple to break inversion symmetry, melting processes as a response to heating and a new type of polymorphism. Given their role as model systems for understanding structure-property relationships, investigating their mechanical properties, such as the bulk modulus (B), Young's modulus, hardness and material stability, becomes increasingly important. Since the material's crystal chemistry ultimately determines its properties, studies related to the mechanical properties address both our fundamental interest in the search for structure-property principles and operational concerns such as material processability and material longevity. The compositional variability of molecular perovskites enables us, therefore, to identify the underlying structure-chemical principles that determine a material's solidstate cooling performance.