Abstract: As the world seeks to increase ambition rapidly to limit global warming to 1.5 °C, joint leadership from the world's largest greenhouse gas (GHG) emitters—the United States (U.S.) and China—will be critical to deliver significant emissions reductions from their own countries as well as to catalyze increased international action. After a period of uncertainty in international climate policy, these countries now both have current leadership that supports ambitious climate action. In this context, a feasible, high-impact, and potentially globally catalytic agreement by the U.S. and China to phase out coal would be a major contribution toward this global effort. We undertake a plant-by-plant assessment in the power sector to identify practical pathways for a 2030 coal phaseout in the U.S. and a 2045 coal phaseout in China in line with national priorities and the global 1.5 °C target. We demonstrate that such pathways would also lead to significant emissions reductions, lowering overall global energy-related CO2 emissions by about 9% in 2030 relative to 2020. A catalytic effect from the possibility of other country phaseout commitments is estimated to reduce global emissions by 5.1 Gt CO2 in 2030 and by 10.1 Gt CO2 in 2045. Subnational coal retirement pathways show heavier impacts for certain coal-intensive regions in both countries. Due to substantial variations of the existing coal fleets, the 1.5 °C-compatible pathways will result in an average retirement age of 47 years for the U.S. coal plants but only 22 years for Chinese coal plants.