Colloidal nanocrystal frameworks (CNFs) are a modular class of mesostructured porous materials, which are assembled from pre-formed nanocrystal building units using suitably designed block copolymer architecture-directing agents. The functional attributes of these frameworks are determined both by the physiochemical characteristics of the nanocrystal components as well as their ordered arrangements in space. It is noteworthy that their assembly schemes are readily amenable to more than one type of framework component, yielding a multivariate landscape to navigate mesoscale phenomena arising from the coupled interactions of different nanocrystals within the framework. Early reports indicate surprisingly efficient propagation of both matter and energy within and along the surfaces of these frameworks, although there remains much to be learned about the origins of their structural, electronic, and dynamic properties, and how they feed back across multiple length and time scales.