The Age of Youth tackles the complicated relationship between youth, national security, and education from World War I to World War II. It reveals how the United States created a time-specific political and social category of youth that relied on the expectation that military-age men should devote themselves to the future of their country. Analyzing policies from the Reserve Officers' Training Corps, the New Deal, wartime military training programs, and those governing the post-World War II occupation of Japan, Masako Hattori demonstrates that the priorities of national security conditioned young people's access to education in the US in the first half of the twentieth century, in both wartime and peacetime, and explores how the evolving link between youth, education, and national security shaped and reshaped the cultural concept of “youth” in American society.

Winner, 2026 Shimizu Hiroshi Book Award, Japanese Association for American Studies

‘Masako Hattori blends the histories of youth, education, and national security to tell a bigger story about the varied and profound impacts of world wars on American society. She even takes us to postwar Japan, offering a fascinating and original comparative of how young people on opposing sides of the war experienced its end. Most of all, this study invites us to ponder anew an uncomfortable but resilient belief in American culture: that war abroad can foster social reform at home.'

Laura McEnaney - author of Postwar: Waging Peace in Chicago

‘Masako Hattori offers an original and provocative socio-political look at the rise of a national security state during the long World War I era. She convincingly upends assumptions about youth and education by redefining them in the context of national security concerns. A brilliant look at diplomacy and its domestic roots.'

Tom Zeiler - University of Colorado Boulder

‘Masako Hattori’s book is well researched and clearly written. She cites a wide range of government documents and records from nongovernment organizations. Building on that framework, Hattori’s study of youth policy provides the opportunity to look further at the range of experiences for young Americans during this important period in the history of American youth.’

Kriste Lindenmeyer Source: The American Historical Review

‘Masako Hattori’s skillful exploration of understudied moral and political undercurrents of the United States’ rise into a military superpower … offers fresh insights into lesser-known programs, policies, and institutions that helped to normalize military education in a country where distrust of standing armies and centralized power had a long history.’

Source: Diplomatic History

‘Hattori adds to our interpretive vocabulary by using the word 'transwar' instead of interwar. By using transwar, she argues that the youth mobilization of World Wars I and II was not separated by a period of peace and isolationism.’

Source: Pacific Historical Review

‘Masako Hattori’s skillful exploration of understudied moral and political undercurrents of the United States’ rise into a military superpower... offers fresh insights into lesser-known programs, policies, and institutions that helped to normalize military education in a country where distrust of standing armies and centralized power had a long history.’

Mischa Honeck Source: Diplomatic History

‘The author makes a compelling case … Hattori’s work is a useful addition to the study of the messy questions surrounding childhood and youth in the early twentieth century that have yet to be resolved.’

Pamela Riney-Kehrberg Source: Pacific Historical Review