This Progress Report shows that, in addition to molecular functional groups, undercoordinated metal sites, porosity, and large surface areas, a further possibility of property control can be incorporated into crystalline framework materials, such as COFs and MOFs: If aromatic molecules are placed in well-controlled stacks, the proximity effect gives raise to strong electronic effects. If the intermolecular distance between the basal planes of the aromatic molecules is in the range of the interlayer distance of graphene (~3-3.5 Å), disperse electronic bands emerge, resulting in a ballistic charge carrier transport with appreciable mobilities. Thus, while the electronic properties of most framework materials are merely the superposition of the electronic properties of the constituting molecular building blocks, a suitable stacking of aromatic building blocks can turn them into semiconducting materials with particular electronic and optoelectronic properties.