The collection contains approximately 1200 letters sent to Dr. Charles F. W. McClure (Princeton Class of 1888), a professor in the Princeton University Biology Department, by numerous biologists and anatomists from the international academic community. A sizable portion of the correspondence is between McClure and his close associates, including his former instructor Henry Fairfield Osborn (whom McClure would later succeed at Princeton) and his frequent collaborator, George Sumner Huntington, professor of anatomy at the Columbia University College of Physicians and Surgeons.

McClure studied a wide variety of animal specimens, both living and dead. During his time at Princeton, he built a comparative anatomical collection using specimens from a number of sources including zoos, circuses, and animal dealers. Correspondence with early 20th-century animal dealers such as William Bartels and J.S. Edwards documents this practice.

Also included in the collection are some of McClure's writings, speeches, and lecture notes, research and teaching files, diaries, and photographs. Some items of note include a diary McClure kept while at Woods Hole, Massachusetts in 1888; a diary of a trip to Greenland in 1899 as part of the Peary Relief Expedition; and a set of negatives and lantern slides of photographs from botanist David Fairchild from his research and travels as part of the Allison V. Armour Expeditions of 1925-1927. Geography and plant life from Europe, North and West Africa, the Canary Islands, and South Asia are documented in these photographs.

In addition, there is an essay, "The Monastery," in which McClure describes the living arrangements of various groups of faculty (himself included) at Princeton from the 1880s until 1937. There are also drafts of a speech, "The Early Life of Charles F.W. McClure", which chronicles McClure's childhood in Massachusetts, his time as a sheepherder in Texas, his decisions to attend Princeton and to study biology, and the course of his career.