Specializing in Americana and particularly North American history prior to the twentieth century, the holdings of the Clements Library are grouped into four categories: Books, Manuscripts, Graphics and Maps.

The library's collection of primary source materials is expansive and particularly rich in the areas of social history, the American Revolution, and the colonization of North America.

The library's initial collections were donated by Clements, an avid collector of materials relating to the discovery of the Americas by Europeans and the American Revolution.

Detroit architect Albert Kahn designed the building "in the Italian Renaissance style, based on Vignola's casino for the Villa Farnese, ca.

[7] From 1935 to 1945 Howard Henry Peckham was manuscript curator, during which time Clements Library was acquiring collections that established an international reputation for itself as an institution for the study of the Revolutionary War and British Colonial America.

The Manuscripts Division cares for approximately 2,600 collections of letters, documents, diaries, financial records, and other materials, with an emphasis on 18th- and 19th-century North America.

[13] William L. Clements began to collect manuscripts in the early 1920s and, with the library's first director Randolph Adams, acquired many of the cornerstone collections of the manuscripts division, including the papers of British Prime Minister William Petty, 2nd Earl of Shelburne; commanders-in-chief of the Army in North America Thomas Gage and Henry Clinton; abolitionists Angelina Grimké, Sarah Grimké, and Theodore Weld; and others.

Many of the latter came to the library with manuscript collections such as the Gage and Clinton papers, which makes the holdings particularly rich in the cartography of the American Revolution.

William L. Clements had a modest collection of portrait prints and a few Revolutionary War cartoons when he founded the library in the 1920s but he showed little interest in visual materials.

The Associates program was created in 1947; and it is estimated that the members have helped purchase "$5,000,000 worth of historical material that today has a monetary value many times that amount.