Papers encompass Kohler's entire career in the Foreign Service (1931-1967), including his four years as ambassador to the USSR (1962-1966) and his ten years at the University of Miami's Center for Advanced International Studies (1968-1978). The collection includes correspondence with his wife, Phyllis Penn Kohler, both before and after their marriage as well as letters from such prominent leaders as Hubert Humphrey; Richard Nixon; Elbridge Durbrow; and Averell Harriman. Files on Kohler's speeches includes his notes, itineraries, and other materials related to speeches in general and notes for meetings with Premier Nikita Kruschev and other Soviet dignitaries. Consultations and conference files detail Kohler's work as a consultant to many advisory panels from 1967 to 1978. Subject files in the collection include two noteworthy files on Germany that date from 1958 to 1959, a crucial period in east-west relations. Other series in the collection document Kohler's activities with the National War College, the Committee on the Present Danger, Radio Free Europe, Radio Liberty, the Communist Party of the Soviet Union, and the Voice of America. Many photographs document the Kohlers' private and public lives, and newspaper clippings; sound recordings; oral history tapes; and memorabilia support these extensive papers.