The Motley Collection of Theatre and Costume Design is a valuable source of documentation on the history of theatre and is housed in The Rare Book and Manuscript Library. It is a rare collection of original materials on the theatre comprising over 5000 items from more than 150 productions in England and the United States. These materials include costume and set designs, sketches, notes, photographs, prop lists, storyboards, and swatches of fabric.

The Motley Group consisted of Margaret Harris, her sister Sophia Harris, and Elizabeth Montgomery, who designed sets and costumes from 1932 to 1976 for plays by Shakespeare and modern classics, opera, ballet, and motion pictures. Their designs were used in productions in the West End of London, the Royal Shakespeare Theatre, the English National Opera, and in the United States on Broadway and the Metropolitan Opera in New York City.

Their first work was for a 1932 production of Romeo and Juliet directed by John Gielgud. The Motley Group was highly innovative in designing sets and costumes that suggested the mood, architecture, and styles of the original setting of the play, but was not the rote duplication that had been done so many times before. They wanted to create an atmosphere that was artistic, in addition to having an air of authenticity. Motley set the standard for how Shakespearean productions should be staged. The Group's work diversified in 1940 when Margaret Harris and Elizabeth Montgomery went to New York to design a production for Laurence Olivier and had to remain there for the duration of World War II, while Sophia Harris worked in London. After the war Margaret Harris returned to London and Elizabeth Montgomery stayed in New York, where she designed the costumes for numerous Broadway musicals, as well as plays, ballets, and operas.

After the members of the Motley Group had retired, Michael Mullin, a professor of English at the University of Illinois at Urbana-Champaign, met Margaret Harris and expressed an interest in the University acquiring the over 40 years worth of designs that the group had accumulated. After long negotiations with Sotheby's, who had been contracted to auction the items, the University of Illinois finally reached an agreement in April, 1981, to purchase the entire collection. This ensured that a valuable resource on the history of 20th century theatre would be preserved intact for the benefit of future generations. For more information, visit the Rare Book & Manuscript Library.