This intellectual biography of Hans Kohn (1891-1971) looks at theories of nationalism in the twentieth century as articulated through the life and work of its leading scholar and activist. Hans Kohn was born in late nineteenth-century Prague, but his peripatetic life took him from the Revolutionary-era Russia to interwar-era Palestine under the British Empire to the United States during the Cold War. Bearing witness to dramatic reconfigurations of national and political identities, he spearheaded an intellectual revolution that fundamentally challenged assumptions about the "naturalness" and...