Precision measurements of the cosmic microwave background (CMB) have been among the most powerful probes of cosmological physics, providing information about the structure and matter content of the universe. Even more precise measurements of the CMB and its polarization have the potential to constrain additional physics: testing models of inflation that operate at energy scales of ~1e16 GeV, constraining the sum of the neutrino masses, and probing dark energy. The 3rd-generation of receiver for the South Pole Telescope (SPT), SPT3G, will provide a major advance in CMB sensitivity using an array of 16,000 bolometers operating at 90, 150, and 220 GHz—10 times more detectors than the existing receiver of the SPT. In addition to the scientific motivation for this new instrument, I will describe technical developments in pixel architecture, readout electronics, and optics which enable the large increase in detector count in SPT3G, as well as the status of final ongoing integration occurring at Fermilab before shipping to the South Pole in November. Finally, I will highlight some recent results from the existing receiver on the SPT, SPTpol, to illustrate the prospects for SPT3G.