Retrieved after World War II from metal boxes and milk cans buried beneath the ruins of the Warsaw Ghetto, the Oyneg Shabes–Ringelblum Archive was clandestinely compiled between 1940 and 1942 under the leadership of historian Emanuel Ringelblum. Members of the secret Oyneg Shabes organization gathered thousands of testimonies from natives of Warsaw and refugees from hundreds of other localities, creating a documentary record of the wartime fate of Polish Jewry. Now housed in the Jewish Historical Institute in Warsaw, the archive comprises some 35,000 pages, including documents, materials from the underground press, photographs, memoirs, belles lettres, and much more. This first comprehensive description of its contents is meticulously indexed to facilitate location of documents and information. By aiding access to this unique archival treasure, the catalog and guide advance study of the daily lives, struggles, and sufferings of Polish Jews at a crucial time and place in the history of the Holocaust.