Abstract: The Spallation Neutron Source accelerator, which produces a 1.4-MW pulsed proton beam to a liquid mercury target for neutron spallation, is undergoing its first series of machine upgrades since the start of operations in 2006. The Proton Power Upgrade (PPU) will double the beam power to 2.8 MW, with delivery of 2.0 MW to the existing first target station. The follow-on Second Target Station (STS) project will add a second target station using 700 kW for production of cold neutrons. The increase in beam power necessitates research and development in certain key areas, including targets, charge-exchange technologies, and beam loss control. This talk will review the PPU and STS upgrade project scope and schedule and highlight key research projects critical to operation at 2.8 MW and future higher beam powers.