The Carter mss., 1956-1978 contains the correspondence between science-fiction authors Lyon Sprague De Camp (1907-2000) and Linwood "Lin" Vrooman Carter (1930-1988). De Camp was born in New York City, and went on to attend Trinity School and the California Institute of Technology. As an undergraduate he studied aeronautical engineering, and later received his Masters in Engineering from the Stevens Institute of Technology. He is known for coining the noun-form of the word "extraterrestrial" and its abbreviation "E.T.," as well as countless science fiction and fantasy stories: most notably, Land of Unreason (1942) (with Fletcher Pratt) and The Dragon of the Ishtar Gate (1961).

Linwood Vrooman Carter was born in Florida, and went on to study at Columbia University. Between 1851 and 1853, he served in the United States Army. He was also a member, alongside Isaac Asimov and Camp, of the Trap Door Spiders: a literary dining club that later became fictionalized by Asimov. Carter is known for science fiction novels, especially his Callisto and The Mysteries of Mars series of books. The collection includes letters from Camp to Carter, spotlighting some of their literary works in progress.