Utilising archives in mainland China, Taiwan, Japan and the USA, Nagatomi Hirayama examines the pivotal role of the Chinese Youth Party in China in the transformative years 1918-51. Tracing the party's birth in 1923 during the May Fourth movement, its revolutionary path to the late 1930s, and its de-radicalization in the 1940s, Hirayama discusses the emergence of the Chinese Youth Party as a robust revolutionary movement on the right, characterized by its cultural conservatism, political intellectualism, and national socialism. Although its history is relatively unknown, Hirayama argues that the Chinese Youth Party represented a serious competitor to the Chinese Communist Party and Guomindang, and proved to be of particular significance during World War II and China's Civil War. Shedding light on the ideas and practices of the Chinese Youth Party provides a significant lens through which to view the Chinese radical right in the first half of the twentieth century.