Qualtitative data. The archival documents in these files support and illustrate conclusions drawn in my monograph, The Rise of Investor-State Arbitration: Politics, Law, and Unintended Consequences (Oxford University Press, 2018). The monograph's central research question is: what explains the rise of investor–state arbitration? These documents primarily reflect conversations, meetings, and letters between national officials and international officials, between the years 1954 and 1994. Most documents are from 4 national archives: the German Federal Archives (Bundesarchiv Koblenz), the National Archives of the United Kingdom, the Swiss Federal Archives (Bundesarchiv Bern), and several archives of the United States government. Select documents are from the Institute of Contemporary History (Institut für Zeitgeschichte), from the National Archives of New Zealand, and from the World Bank Group Archives.