These papers include two pages by Rubens Peale concerning landscapes, a notebook by Rembrandt Peale relating to the portrait of Washington, and a commonplace and recipe book, with sketches of gas lights.

These papers include diaries (1777-1782), expense books (1794-1804), notebooks, a commonplace book, drafts of essays, excerpts from minutes of Friends' Monthly Meeting, Tortola (1741-1761), newspaper clippings, sketches, and correspondence. Also included are letters and papers of Mrs. Thornton.

The papers include miscellaneous letters, letterbooks, books, certificates, and diplomas of various members of the Muhlenberg family. Among them are photostats of letters and papers of General John Peter Gabriel Muhlenberg and officers of the Continental Army on military affairs in the Southern Department during the American Revolution (1772-1804); photostats of letters to Albert Gallatin, Nathanael Greene, Edward Hand, Winthrop Sargent, Baron von Steuben, William Alexander, and George Washington; photostat of General Muhlenberg's journal of trips to the Ohio (1784, 1797); photostats of letters and notes of Gotthilf H. E. Muhlenberg, including a diary kept at Halle (1771) and extracts of thirty letters to Stephen Elliott of Beaufort and Charleston, South Carolina (1808-1815); photostats of letters of Henry A. Muhlenberg about his biography of General Muhlenberg (1848-1849); and photostats of letters of Henry Melchior Muhlenberg (1711-1787). Also included is an original letterbook of Peter Muhlenberg, paymaster of the United States Army, kept at Augusta and Savannah, Georgia (1836-1842). Henry Muhlenberg's notebooks (1784-1813), written in Latin or German script, in a small hand, includes a wealth of botanical observations, with a focus on Lancaster, Pennsylvania. The Henry Muhlenberg journals are a record of daily occurrences, with many features of a commonplace book, containing prescriptions, notes of questions asked candidates for the Lutheran ministry, and the plan of a barn. There is also a biographical account of Rev. Henry Melchior Muhlenberg (1711-1787).

The Peale family is best known as a family of artists; however, family interests and activities were much more wide-ranging. The best known Peale is Charles Willson Peale (1741-1827, APS 1786), who produced more than one thousand paintings, including hundreds of portraits of leading Americans during the colonial and early national periods. Peale was married three times, to Rachel Brewster (1744-1790), Elizabeth de Peyster (1765-1804), and Hannah More (1755-1821). He had eighteen children, eleven of whom reached adulthood. Three of Charles Willson Peale's sons became artists: Raphaelle Peale (1774-1825), Rembrandt Peale (1778-1860), and Rubens Peale (1784-1865). A fourth son, Titian Ramsay Peale (1799-1885, APS 1833), was a naturalist (who made drawings on the exploring expeditions he accompanied) and pioneer in photography, and another son, Benjamin Franklin Peale (1795-1870), became a naturalist and paleontologist. Peale's daughter Sophonisba Angusciola was married to Coleman Sellers (1781-1834), an inventor and manufacturer of machinery, including locomotives. Two of their sons, George Escol Sellers (1808-1899) and Coleman Sellers (1827-1907, APS 1872), were inventors and engineers. The latter served as director of the construction of the hydro-electric power development at Niagara Falls. He was married to Cornelia Wells Sellers (1831-1909). One of their grandsons was Charles Coleman Sellers (1903-1980, APS 1979), a librarian and historian and the author of several studies of the Peale family, including a Charles Willson Peale biography.