This article examines Guomindang institutional rationalization during the Sino-Japanese War and its implications. The author argues that the war witnessed the most intensive Guomindang efforts of state building characterized by rationalization of state institutions. Drawing intellectual resources from theories of public administration in the United States, the Guomindang pushed for institutional rationalization by implementing a three-in-one administrative system through the integration of planning, execution, and assessment. The Guomindang succeeded in creating institutions of central planning and assessment and increased the rationalization of state institutions but failed to achieve the level of administrative efficiency it had hoped for. Guomindang institutional rationalization contributed to the Guomindang's and the Communists' recognition of the desirability of central planning and a planned economic system. It also began the process of designating political, economic, and administrative organizations as danwei.Scholars of modern China have long appreciated the critical importance of the Sino-Japanese War in key historical developments. As many studies have shown, the war fostered the development of Chinese nationalism, hastened the collapse of the Guomindang regime,