Advances in manufacturing technologies are enabling the development of 3D multi-processor ICs, but heat in 3D stacking can lead to degraded performance due to higher power density, which derives from the placement of computational units and storage components on top of each other. Since it is more difficult to remove the heat from 3D ICs, cooling can become the main limiting factor for future 3D multiprocessor system-on-chip (MPSoCs). This paper presents a novel thermal-aware design paradigm for 3D ICs, which includes thermal modeling as a fundamental step to design 3D with inter-tier liquid cooling as well as system-level dynamic thermal management to tune the coolant flow rate to achieve energy-efficient thermally-balanced 3D MPSoCs