Flip-flops in a monolithic three-dimensional (3D) integrated circuit (IC)(3DIC) and related method are disclosed. In one embodiment, a single clock source is provided for the 3DIC and distributed to elements within the 3DIC. Delay is provided to clock paths by selectively controllable flip-flops to help provide synchronous operation. In certain embodiments, 3D flip-flop are provided that include a master latch disposed in a first tier of a 3DIC. The master latch is configured to receive a flip-flop input and a clock input, the master latch configured to provide a master latch output. The 3D flip-flop also includes at least one slave latch disposed in at least one additional tier of the 3DIC, the at least one slave latch configured to provide a 3DIC flip-flop output. The 3D flip-flop also includes at least one monolithic intertier via (MIV) coupling the master latch output to an input of the slave latch.