From 1935 to 1950, Chiang Kai-shek steered China’s development as a nation and shaped global history. Yet he remains an enigmatic figure remembered primarily for losing a decisive civil war. A reinterpretation is overdue. Based on Chiang’s own writing, particularly his diary, Chiang Kai-shek’s Critical Years sheds new light on his call for mobilization against Japan in 1937 and his relations with US representatives during the war; his efforts first to accommodate and then to defeat the Chinese Communist Party; and his ability to hold on to the presidency of the Republic of China after 1949, despite disastrous military failure. This examination of Chiang’s daily planning and reflection on events reveals astute improvisation that ensured political survival despite setbacks and weaknesses. The sharpened sense of Chiang’s agency that emerges from this important book provides an invaluable foundation for further analysis of the military and political institutional structures he helped build.