The Rockefeller Foundation's Transforming Health Systems (THS) initiative (2008-2017) aimed to strengthen health systems in low and middle income countries to promote Universal Health Coverage (UHC). The initiative successfully catalyzed a global movement towards UHC, influencing key policy agendas, creating enduring networks, and providing substantial grants while facing challenges in certain focus countries. This final evaluation assesses THS's achievements, lessons learned, and its lasting impact on global health systems and UHC efforts.