Monolithic 3D ICs employing one or more local inter-level interconnect integrated intimately with at least one structure of at least one transistor on at least one transistor level within the 3D IC. In certain embodiments the local inter-level interconnect intersects a gate electrode or a source/drain region of at least one transistor and extends through at least one inter-level dielectric layer disposed between a first and second transistor level in the 3D IC. Local inter-level interconnects may advantageously make a direct vertical connection between transistors in different levels of the 3D IC without being routed laterally around the footprint (i.e., lateral, or planar, area) of either the overlying or underlying transistor level that is interconnected.