The Countries and Regions subcollection of the Geneva Collection for the years 1945-1954 includes material on 71 separate countries and regions at the record group level. This material consists of correspondence, cables, reports, statistical material, names lists, audits, minutes of meetings, and other documents that chronicle the activity of JDC to rebuild Jewish life in Europe and provide aid to Jews and Jewish communities throughout the world during these years. In displaced persons camps in Germany and Italy and in devastated Jewish communities throughout Europe, JDC supplied food, clothing, and equipment; set up cultural and vocational training programs; provided medical care; distributed educational and religious materials; and provided legal representation and emigration assistance. Medical efforts included an extensive care system for treatment and reintegration of tuberculosis patients. The subcollection also details JDC's aid for emigration to Israel and countries of immigration around the world. JDC facilitated these movements through its own emigration offices and cooperation with other international organizations such as the International Refugee Organization and Jewish organizations including the Jewish Agency and HIAS (Hebrew Immigrant Aid Society).

Another major aspect of the JDC program was support for economic reconstruction through the establishment of loan institutions and support for new producer cooperatives. This subcollection also documents the negotiations between JDC and military and diplomatic personnel stationed in Germany regarding the passage of survivors and refugees from countries in Eastern Europe to the safety of the American Zone in Germany. It contains JDC Legal Department files with detailed information on Nazi war criminals. It also sheds light on the JDC Location Service that worked to reunite survivors. Another aspect of the JDC's work was to provide legal aid to Jewish communities to document heirless Jewish property and achieve restitution for such properties. Whereas JDC operated directly in the DP camps, its activities in most countries were conducted through local Jewish communities and institutions or by subvention of international Jewish organizations providing specific types of services. This subcollection chronicles how JDC was instrumental to differing degrees in recreating, funding, and guiding Jewish communal institutions in the various countries of Europe.

The subcollection also includes information on the initiation and growth of JDC programs in North Africa and the Middle East, particularly in the fields of health, education, and aliyah. By far the most extensive material on an individual country appears in the Germany record group, but there are also significant amounts of material from Austria, France, Hungary, Israel, Italy, Morocco, Poland, Romania, and Switzerland. In addition to documenting the services provided by JDC, the subcollection contains extensive information on administrative and financial matters, including budgets, audits, JDC offices, and material relating to the complex currency transactions involved in running an international aid organization during this period.