Abstract On-chip interconnects are predicted to be a fundamental issue in designing multi-core chip multiprocessors (CMPs) and system-on-chip (SoC) architectures with numerous homogeneous and heterogeneous cores and functional blocks. To mitigate the interconnect crisis, one promising option is network-on-chip (NoC), where a general purpose on-chip interconnection network replaces the traditional design-specific global on-chip wiring by using switching fabrics or routers to connect IP cores or processing elements. Such packet-based communication networks have been gaining wide acceptance due to their scalability and have been proposed for future CMPs and SoC design. In this chapter, we study the combination of both three-dimensional integrated circuits and NoCs, since both are proposed as solutions to mitigate the interconnect scaling challenges. This chapter will start with a brief introduction on network-on-chip architecture and then discuss design space exploration for various network topologies in 3D NoC design, as well as different techniques on 3D on-chip router design. Finally, it describes a design example of using 3D NoC with memory stacked on multi-core CMPs.