A single crystal to single crystal [2+2] photodimerization has been achieved within a molecular cocrystal composed of finite, hydrogen-bonded molecular assemblies using the absorption-edge irradiation technique. The cocrystal is composed of a resorcinol template and a diolefin reactant that reacts to form a non-symmetrical cyclobutane product. The product is an intermediate in a two-step solid-state synthesis of a [2.2]paracyclophane. The ability to conduct the reaction in a single crystal to single crystal fashion attests to the robustness of the hydrogen-bonded assemblies during the course of the solid-state transformation.