The Leon Katz Papers consists of research files, writings, personal and professional papers, correspondence, subject files, photographs, printed materials, computer media, and audiovisual materials by or relating to Leon Katz. The collection documents Katz's lifelong study of Gertrude Stein; included are extensive research files, notes, drafts, and Stein's correspondence with notable associates, such as Mabel Dodge Luhan, Ernest Hemingway, Henri Matisse, Pablo Picasso, Leo Stein, Mabel Weeks, and Carl Van Vechten. It also includes a card index and transcripts of Katz's interviews with Stein's partner, Alice B. Toklas, as well as Katz's doctoral thesis about the earliest drafts of Stein's novel The Making of Americans, and drafts of his book The Notebooks of Gertrude Stein. Personal and professional papers contain Katz's other books, anthologies, plays, scripts, articles, and reviews by Katz, in addition to teaching files, artwork, and personal financial records. Correspondence and subject files include letters between Katz and notable individuals such as Meiling Cheng, Ulla Dydo, Donald Gallup, Peter Golub, Virgil Thomson, Alice Toklas, and his son, writer Elia Katz. Also present within the collection are translations, plays, books, and articles by other writers, including Conrad and Linda Bishop, Donald Freed, Georgi Iliev, Elia and Fred Katz, Rose Martula, and Orson Welles. Photographs contain images of Katz and his family, as well as images from theater productions. Printed materials contain books, serials, and broadsides. Computer and audiovisual media consist of compact discs, DVDs, floppy disks, videocassettes, audiocassettes, and audio discs.