In 1960 millions of Japanese citizens took to the streets for months of protest against the U.S.-Japan Security Treaty (Anpo) and its forcible ratification by the Kishi government. In the decades that followed, the Anpo era citizens’ movements exerted a major influence on the organization and political philosophies of the anti-Vietnam War effort, local residents’ environmental movements, alternative lifestyle groups, and consumer movements. Organizing the Spontaneous departs from previous scholarship by focusing on the significance of the Anpo protests on the citizens’ drive to transform Japanese society rather than on international diplomacy. It shows that the movement against Anpo comprised diverse, at times conflicting, groups of politically conscious actors attempting to reshape the body politic.