Pass-through 3D interconnects and microelectronic dies and systems of stacked dies that include such interconnects are disclosed herein. In one embodiment, a system of stacked dies includes a first microelectronic die having a substrate, a metal substrate pad, and a first integrated circuit electrically coupled to the substrate pad. A pass-through 3D interconnect extends between front and back sides of the substrate, including through the substrate pad. The pass-through interconnect is electrically isolated from the substrate pad and electrically coupled to a second integrated circuit of a second microelectronic die attached to the back side of the substrate. In another embodiment, the first integrated circuit is a first memory device and the second integrated circuit is a second memory device, and the system uses the pass-through interconnect as part of an independent communication path to the second memory device.