Documents relating to Andalusia Gardens include account books, photographs, correspondence, clippings, planting plans, drawings, and other materials. A working copy of a finding guide is available on-site, although the materials have not been fully processed and some materials are currently restricted or can only be viewed with advance notice.

Charles J. Biddle's (1890-1972) papers that relate to Andalusia are largely uncataloged and filed in date order according to his system. Only a select few are available for researchers. Photographs are mainly in family photo albums. Earlier agriculture pursuits are contained in collections of individuals. The earliest relevant item is a Nicholas Biddle account book, 1821-1838 (particularly a folder on the "Grapery and Mansion House"). Letitia Glenn Biddle's garden journal, a small diary, her guest book, and miscellaneous papers reveal early 1900s gardening at Andalusia. James Biddle's collection (1929-2005) [some items restricted] mainly shows gardening in the 1980s and 90s. Also available is a 2011 survey of trees on the property with identification, photos, and database prepared by Heather Schmidt, Temple University student.

The letters in this particular collection were attached to large sheets of paper, organized, and bound into a volume in 1916. A finding aid with an item-level inventory is available on-site. The Biddle Papers, Andalusia contains letters beginning with Charles Biddle in the late eighteenth century [small in number, see the Papers of Charles Biddle 1793-1817 for more letters] and continues with his descendants to 1951. There are also newspaper clippings, receipts, and other miscellaneous documents with the greatest concentration in the early to mid nineteenth century.

Personal correspondence includes letters to and from Nicholas Biddle (1786-1844) beginning as a student at Princeton, and later, letters from his own sons. Some correspondence relates to Nicholas Biddle as a member of the Pennsylvania House of Representatives while letters from architect Thomas U. Walter discuss expansion of the mansion at Andalusia. A letter from William Barton thanks Nicholas Biddle for his "hint" regarding his book about Dr. Rittenhouse; a list of books owned by Nicholas Biddle in 1803 reveals that many of these books remain in the Andalusia library.

Letters from John Biddle (1792-1859) recount experiences during the War of 1812; later letters were written while serving with the army in Detroit and as territorial Governor. Also of military interest is a letter from Commodore William Bainbridge to Nicholas Biddle which includes a few pages of memoirs.

Of agricultural interest are letters regarding the Guernsey cattle purchased by Nicholas Biddle in 1840 and a short history of the American Guernsey Cattle Club; the last of the Biddle's Guernsey cattle were sold in 1951.

Commodore James Biddle (1783-1848)'s papers at Andalusia are largely organized into sixteen bound volumes of letters, 1798-1848, and miscellaneous documents. In addition, there are: newspaper clippings, letterbooks and journals, copybooks providing information in preparation for his voyage to China, logbooks including one from the ship Columbus, letters, a silhouette, Mandarin calling cards, a sketchbook (1845-1848) with copies of Biddle's correspondence paired with sketches by artist Edward C. Young illustrating scenes from Biddle's time in the Navy, and other miscellaneous letters and documents. Finding aids are available on site both for the 16 volumes of letters and for the other miscellaneous Commodore Biddle papers.

James Biddle, second son of Charles and Hannah Shepard Biddle, was born in 1783 and died in 1848 after serving in the Navy for forty-eight years. The Letters of Commodore Biddle, 1798-1848 and undated, were attached to large sheets of paper and bound in chronological order into 16 volumes early in the twentieth century. They cover the full range of his time in the Navy and contain both personal letters and military related documents such as courts martial proceedings.

James Biddle was a member of the crew of the ship Philadelphia that in 1803 ran aground on the coast of Tripoli during the Barbary Pirate wars. After spending nineteen months in prison, the crew was freed in an agreement precipitated by General Eaton and a group of men which included nine United States Marines later celebrated in the Marine's hymn "to the shores of Tripoli."

Biddle's exploits during the War of 1812 enabled him to rise in rank much faster than normal; he was awarded a medal and a sword for his deeds. In 1817 Biddle received orders to, among other duties, set the American flag at the mouth of the Columbia River to provide a stronger US claim to Oregon over Great Britain. Upon his return by way of Chile, Biddle became embroiled in a disagreement with British commander Lord Thomas Cochrane over the firing of salutes.

Commander of the West India Squadron during 1823 and 1824, Biddle's role was to deal with piracy although the successes were overplayed by the loss of approximately one third of his crew on the Macedonian to yellow fever. It was a time that historian David F. Long refers to as "the one clear fiasco in a life otherwise characterized by perceptive, diligent, and successful diplomacy." More successful was the Commodore's role in arranging a trade treaty with Turkey in 1830 and taking over from the ill Alexander H. Everett and exchanging ratification of the treaty with China on 31 December 1845. Documents in the collection include letters dealing with other business in China as well as Biddle's instructions from the government to visit as many ports and islands as he can to increase protection to commercial interests abroad. Several documents deal with preparations for the mission; Document #4511 describes the voyage to China, ratification of the treaty, and food served at a "handsome entertainment." Biddle's short stay in Japan's Jeddo Harbor has been a point of controversy; some scholars insist that the Commodore failed in his attempt to open trade with Japan.

Commodore Biddle returned to America by the Sandwich Islands where he learned of the war with Mexico. Document #4513 reveals that Biddle realized that the Columbus was the only ship of the line in commission and, therefore, might be required in the Gulf of Mexico. At Valparaiso he received orders to command the Pacific Squadron, thus, numerous letters deal with local and military matters in California during this time.

Biddle arrived at Norfolk in March 1848 after an almost three year voyage, retired from the Navy and headed for Philadelphia. He died on 1 October, barely six months after his retirement; his remains were interred in his father's vault at Christ Church burial grounds.

There are a large quantity of Letitia Glenn Biddle in this collection, relating largely to gardening, other aspects of maintaining the Andalusia property, and family genealogy. Her papers include: two volumes of film negatives of Europe and Nova Scotia, circa 1900-1910; collected periodicals, 1891-1914; a garden journal and other gardening-related papers; a guest book; a large amount of cancelled checks and other financial papers; correspondence; photographs; and blue prints of Andalusia.

Henry B. Keep, Sr. (1891-1918)'s connection to the Biddle family is through marriage: Keep died in action during World War I shortly after the birth of his son, and his widow, Katharine Jennings Legendre (1893-1973), re-married to Charles J. Biddle (1890-1972). A finding aid to the Henry B. Keep papers is available on-site; there are some additional unprocessed materials, including World War I and World War II-related letters and other papers from Henry B. Keep, Sr. and Jr., respectively.

The Henry B. Keep papers consist of approximately four linear feet and are comprised of the letters, miscellaneous documents, and photo/memorabilia books belonging to Henry B. Keep Sr. (1891-1918), Henry B. Keep Jr., and Chauncy Keep (Henry Sr.'s father). Henry Blair Keep (1891-1918) and Katharine Jennings Legendre were married in New Orleans on 7 December 1916; their son Henry B. Keep Jr. was born on 1 October 1917. Henry Sr., a member of the US Army Infantry during World War I in France, was killed in action in October 1918. Katharine L. Keep later married Charles J. Biddle in 1923, gave birth to Charles (1925) and James (1929) and resided at Andalusia for fifty years.

Henry Blair Keep was born on 25 September 1891 to Chauncy and He was educated at the Hill School in Pottstown, Pennsylvania and Yale College, class of 1915. He joined the Army at the beginning of United States involvement of the War and was commissioned a Lieutenant. He went into the front lines early in July 1918 at the beginning of the Allied Drive at Chateau Thierry, acting in command of his Company, the 10th Machine Gun Battalion of the 4th Division. In August he was commissioned a Captain and had been scheduled for further Officer's training, but at his request was allowed to remain in command of his company that it might have his personal leadership during the ensuing campaign. At the time of his death, Henry Keep had been fifteen days with his Company in the section between the Meuse River and the Argonne Forest. His death was due to a shell which entered a shell hole or crater where he and all the other officers of his Company were sleeping on the night of 5 October 1918. Immediately buried in the southwest corner of the Bois-de-Fay just west of the town of Brieulles on the west bank of the Meuse River, a month later his body, along with those of other officers killed, was moved to the recently established American Military Cemetery at Madelaine Farm about one mile away. Captain Keep's remains were returned to the United States in August 1921.

Just one year after Henry Blair Keep Jr. was born, his father died in action in France, on 5 October 1918. According to a note left by James Biddle (1929-2005) Keep Sr. never saw his son. Photograph albums track Henry Jr.'s years through his time serving in the diplomatic corps in Asia. Letters of interest include one written from Berlin in August 1945 describing the post-war conditions of that city and its inhabitants and letters describing trips to Kashmir, Darjeeling, and Tokyo. Numerous condolence letters written to Keep upon the death of his mother, Katharine Legendre Keep Biddle in 1973 illustrate the great number of individuals whose lives she touched. Likewise, estate papers and condolence letters written to James Biddle when Keep died in 1983 reveal that he too, was a generous and caring friend. Correspondence reveals that museum bequests include the University of Pennsylvania Museum and the Far East Department of the Philadelphia Museum of Art.

Nicholas Biddle, Jr. (1917-2013) accumulated materials from his Biddle predecessors, 1784-1949, including approximately 450 letters and documents, 3 notebooks, 24 pamphlets, 3 journals/diaries, 1 photograph album, 2 glass-plate negatives, 1 handwritten book of copies of letters, 1 commonplace book, 2 ledgers, 1 published book, 6 newspapers, and 1 historical map. The Nicholas Biddle, Jr. section is being processed as of 2014; an incomplete finding aid exists on site at Andalusia Foundation. Of special interest are: a series of correspondence between James Monroe and Nicholas Biddle, 1807-1828; several letters from Aaron Burr, 1807-1808 and undated; Charles J. Biddle (1819-1873) autograph collection of letters with autographs cut out (most autographs were pasted into a separate album, also available at Andalusia); Nicholas Biddle (1786-1844) Greece Journal No. 1; Nicholas Biddle (1786-1844) personal journal/memoir, 1838-1839 (32 handwritten pages); Jane Craig Biddle, commonplace book, begun 1811 (15 handwritten pages, 1 leaf drawing); Charles Biddle (1745-1821) letterbook with list of Senate members, 1809-1812; and Edward Biddle III (1851-1933) photograph album of Europe, circa 1890.

Gerda Paumgarten is the great-great-great-grandaughter of Nicholas and Jane Craig Biddle through their daughter, Meta (Margaret) Craig Biddle who married her cousin James Stokes Biddle, son of Nicholas's brother Charles. James S. and Meta's son, also named Nicholas, had a daughter also named Meta (1880-1958) who gave birth to Elise Robinson (b. 1906) and married Harald Paumgarten, an Olympic champion from Austria--Gerda's parents.

Much of this series consists of handwritten copies of genealogy reports, letters of historical and family interest, and letters written to Mr. and Mrs. James S. Biddle and Mrs. Nicholas Biddle (Eliza I. Butler) regarding family information. Some of the genealogy information may have been used in the Autobiography of Charles Biddle (1745-1821) edited by James S. Biddle and published by Judge Craig Biddle.

There is a photo of a portrait circa 1840 possibly of James S. Biddle and a corrected proof of a memoir of his life which includes letters from family members and substantial correspondence from his years in the Navy 1833-1856, including letters and observances from the War with Mexico.

Some of the documents are written as the remembrances of Meta Biddle (Mrs. James S.) and copied by Elise Robinson Paumgarten. Other "memoranda of Craig Biddle" (John Craig Biddle (1823-1910) are a compilation of information that he knew and/or found from a variety of sources within the collection.

Of special interest is a journal presumably kept by Mrs. Nicholas Biddle (Eliza I. Butler1845-1904) describing events in the life of her daughter Emily Butler Biddle (b. 1878.) Emily married Charles W. Churchman at Andalusia in 1903.