Family and personal papers include correspondence between George Bancroft and his first wife, Sarah Dwight (d.1837), his second wife, Elizabeth Davis Bliss, his father, Aaron Bancroft, his sister, Eliza Bancroft Davis, her husband John Davis, Governor of Massachusetts, his sister, Lucretia Bancroft Farnum, his two sons, George Bancroft, Jr., and John Chandler Bancroft during their school days and their travels abroad; other family letters are from other sisters and brothers, members of the Dwight family, Bancroft's two stepsons, Alexander and William Bliss, nieces, nephews, and other relatives; early deeds, other legal documents, papers pertaining to the settlement of various estates, and considerable genealogical material. Business and professional correspondence includes letters describing his involvement in Dwight family business interests, his stock holdings, and his work for the Bank of Michigan and other private banking ventures; letters and contracts with Little, Brown & Company detail his publication problems; and correspondence with his brokers and with his sons documents his later financial affairs, especially the income from his writings. There are some rough notes for his books and notes from personal interviews with Louis Philippe and Bismark. His political and diplomatic interests are documented by correspondence describing life in Washington, D.C., his career as Collector of the Port of Boston, and his advent as a cabinet official under Polk, as well as the Civil War and Reconstruction.

Correspondence documents his appointments as Minister to Great Britain in 1849 and Minister to Berlin, 1849-1867. There is also a series of letters to his wife in 1847 discussing French politics in detail as well as his reaction to French historians and philosophers. In addition, the collection contains a large number of autographed letters from persons prominent in public affairs and the literary world in Europe and America, 1817-1886; albums of photographs of the German royal family and others; bronze plaque honoring Bancroft; 90th birthday scrapbook; guest book, 1894-1899; and two letters, 1941, to Wilder D. Bancroft from the U.S. Navy regarding the launching of a ship named for George Bancroft; 15 letters (1906) from British scientist to Sir William Ramsay pertaining to Wilder's suggestion that the Journal of Physical Chemistry be printed in England, and clippings (1923) relating to Wilder's experiments in rainmaking. Included is correspondence by or about Ann Bancroft, Mary Bancroft, Sarah Bancroft, Thomas Bancroft, Alexander Bliss, William Bliss, T. Hartley Crawford, Jonathan Dwight, Jane Putnam Bancroft Gherardi, D. Goodwin, William Murphy, Henry Schoolcraft, Charles C. Trowbridge, Baxter Witter, and Levi Woodbury.