The records consists of incoming, outgoing, and interoffice correspondence across all divisions and activities of ONE Inc., 1952-1994. The records document requests for information and assistance, research and collaboration offers, publication orders, membership, outreach and media relations, office administration, educational offerings, travel tours, conferences, events, lectures, projects, proposals, business solicitations, and permission requests for use of materials among others. The records include letters, membership forms, memoranda, and occasional subject matter about a person or organization. The files include international correspondence from most Western European countries as well as from Vietnam, Columbia, South Africa, Burundi, Japan, Kenya, Singapore, Ecuador, Valenzuela, Peru, Southern Rhodesia, and Peru just to name a few. The files include correspondence and membership records from all occupations and stations of life from doctors to reverends, lawyers to prisoners, soldiers to activists, administrators to scientists.

Note that although the correspondence series covers all areas of ONE Inc's operations, specific correspondence is also provided in the Publications, Education, Social Service, and Research Division records series as well as in the ONE World Travel Club, Institute for the Study of Human Resources, and satellite offices records series. Note that within the three sections of this series, topical overlap should also be expected.