Intrinsic magnetic order suffers from the large distances between the spin centers in a MOF and the resulting weak couplings in the order of few meV. Thus, they are only observed at cryogenic temperatures. Ballistic transport is typically hindered either by the large effective masses of the typically dispersionless bands or by the chemical composition of the frameworks, where non-carbon centers (for example oxygen, boron or nitrogen) can effectively block electron conjugation. Only recently, ballistic transport, facilitated by electron conjugation, has been demonstrated in layers of two-dimensional (2D) MOFs and COFs. There is, however, a more subtle way to implement strong band dispersion in crystalline molecular framework materials: Controlled stacking of aromatic molecules, incorporated into the materials as linkers or as pillars with suitable intermolecular distance, is subject to the proximity effect, more precisely, the molecules interact via π -stacking, which causes strong alterations of the electronic structure of the framework materials. The proximity effect is the basis of the recent breakthrough in van-der-Waals physics of 2D materials (see, e.g., [31-40]). While this type of stacking is rather obvious for the class of layered COFs with atomically thin layers and with aromatic connectors or linkers, it can also be achieved in MOFs with suitable crystal structure. A further option of MOFs and, to some extent, also COFs is to grow superstructures by applying layer-by-layer procedures (MOF-on-MOF) and to fabricate structurally well-defined organic/organic heterointerfaces. In this Progress Report, we elaborate the impact of the proximity effect in MOFs and COFs with suitable crystal structures. We will first discuss the importance of the proximity effect for the case of graphene, which serves as role model for the stacked aromatic moieties in MOFs and COFs. In order to reach a wide audience with background in chemistry, we will introduce key concepts of solid-state physics, when appropriate. We will then approach the closest relatives to graphene, stacked layered COFs, before we explore pathways to tailor these interactions by means of crystal structure and functional side groups in both layered and threedimensional MOFs. The conclusions include our perspective of further exploiting the proximity effect in crystalline porous framework materials and, thus, exploiting the fusion of most recent advances in the condensed matter physics and materials chemistry. In the experimental section, we give an overview of theoretical approaches, rationally design and to computationally explore these materials, and summarize the layer-by-layer (lbl) growth technique to synthesize surfacemounted MOFs with controlled stacks of aromatic linker molecules.