General Files consist primarily of correspondence: correspondence with authors, correspondence about authors, and correspondence with the heirs of authors regarding royalty dividends and other matters. Author folders may also contain contracts and articles of agreement; copyright registration certificates; requests for permission to reprint; requests to purchase books; inquiries regarding literary, publishing and reproduction rights. Includes correspondence with authors whose manuscripts were rejected. Also contains correspondence with or regarding other publishers, printers and suppliers such as A. L. Burt Company, Curtis Brown Ltd., Cruikshank Publishing Company (see Cruikshank, Frank X.) that produced a basic training manual during World War II, and Grosset & Dunlap.

Most authors who published with McClurg are fairly unknown, but some of the better-known authors include Felix Borowski (Standard Concert Guide/Standard Opera Guide), Edgar Rice Burroughs, Mary Hartwell Catherwood, W. E. B. Du Bois, Byron A. Dunn, Oscar J. Friend, Zane Grey, Edith Ogden Harrison, Margaret Hill McCarter, and Clarence E. Mulford, author of the Hopalong Cassidy books.