The records of the American Jewish Historical Society, the oldest national ethnic historical organization in the United States, include correspondence of officers and staff as well as inter-office memos, multiple versions of the constitution and by-laws of the society, meeting minutes of administrative branches and committees, membership and financial records, reports, exhibit materials, records relating to the society’s library and archival holdings, press releases and newspaper clippings, and publications and newsletters created by the society. There are also materials from various programs, such as meetings and conferences, tours, lectures, awards and dinners, films, and educational programs.

Hadassah Functions and Operations Records represent the bulk of aid and services provided to Hadassah's membership, from the 1920s to 2011. Materials found in the record group include correspondence, clippings, press releases, manuals and kits for chapters and members to implement programming and chapter structure, fundraising campaigns, scripts, study guides, programming for local and national meetings, biographical files, and training documentation. Departments documented in the record group include Public Affairs, Education, Women's Health, American Affairs, Zionist and International Affairs, Speakers Bureau, Fundraising, Program, Organization, Outreach and Tourism Departments. Materials related to the general administration of Hadassah are also in the record group; these materials include research and development of projects, archives department correspondence and other materials, Hadassah House administration, and strategic planning. The record group also documents Hadassah's efforts to expand membership outside of the United States, by the development of Hadassah International.

This collection contains writings, minutes, financial records, correspondence, printed materials, newspaper clippings, and photographs relating to Broido's employment, investments, and Jewish and non-Jewish communal activities. It includes material regarding the department store, Gimbel Bros. (1934-1966), where he was associated with Bernard Gimbel, and where he served as Executive Vice President and as Chairman of the Advisory Committee (1953-1961); Temple Emanu-El (1957-1970), where he served as trustee and opposed secession from the Union of American Hebrew Congregations; the American Jewish Joint Distribution Committee (1944-1976), serving as President from 1965-1975, and where he was involved in the investigation of the Charles Jordan murder in Prague (1967); the Union of American Hebrew Congregations (1953-1972) where he served as trustee and played an active role in financial matters and relations with the Hebrew Union College; the United Jewish Appeal (1941-1972) where he served as President (1951-1952), trustee and member of the Board of Directors; the New York City Community College (1956-1972) where he served as trustee; and the Department of Commerce and Industrial Development of the City of New York (1961-1971) where he served as Commissioner (1961-1966).

The records chronicle the ideology behind the Reconstructionist movement, the founding and activities of the Jewish Reconstructionist Foundation, and its growth and transformation from an ideology and movement into an established American Jewish denomination, Reconstructionist Judaism. The records also document two seminal figures in Reconstructionist Judaism, Mordecai Menahem Kaplan and Ira Eisenstein. Included in the collection are the administrative records of the Foundation (minutes, financial records, bylaws), publications produced by the Foundation including manuscript submissions for the influential publication The Reconstructionist, correspondence, sermons, prayer books produced by the Foundation, syllabi, sheet music, photographs, and speeches, among other material. In the correspondence are letters from Martin Buber, J. Edgar Hoover, and Albert Schweitzer.

The children and descendants of Isaac Mendes and Rachel Levy Seixas included individuals who had a great impact on communal affairs and colonial Jewish life in New York, Philadelphia, Newport, and Richmond. Though this collection does not preserve the total volume of papers produced by every family member, the documents contained herein demonstrate the importance of the family in both Jewish and secular life in late 17th and early 18th century North America.

The collection is valuable to researchers studying the Seixas family; civic, mercantile, and religious contributions of Jews in the colonial era; Jewish communities in New York, Philadelphia, Newport, and Richmond; the importance of religion to Colonial Jews; Jewish participation in the Revolutionary War, the War of 1812, and World War I; Jewish converts to Christianity; Jews as masons; and Congregation Shearith Israel of New York.

Prominent individuals in this collection include: Ephraim Hart, Grace Seixas Judah, Mrs. Jesse Judah, Israel Baer Kursheedt, Sarah Seixas Kursheedt, Hayman Levy, Nicholas Low, Isaac Moses, Naphtali Taylor Phillips, Benjamin Mendes Seixas, David G. Seixas, Gershom Mendes Seixas, Isaac Benjamin Seixas, Isaac M. Seixas, Jacob B. Seixas, Joshua Seixas, and Moses Mendes Seixas.

The collection includes: account records, books, circumcision instructions and register, correspondence, drawings, estate papers, a eulogy, family trees, legal documents, petitions, photographs, prayer books, a sermon, and shipping records.

This collection is arranged into four series: Series I: Family Papers; Series II: Moses Seixas (1744-1809); Series III: Gershom Mendes Seixas (1746-1816) and descendants; and Series IV: Benjamin Mendes Seixas (1748-1817) and descendants.