The William G. B. Carson Papers consists of four accruals:

Accrual 1 includes materials relating to United States theatre history; materials relating to Carson's teaching at Washington University in St. Louis; theatre playbills, programs, magazines, and newspaper articles; correspondence and autograph collection of famous actors, actresses, and writers.

Accrual 2 relates primarily to preparation of Dear Josephine, Professor Carson's biography on Josephine Sherwood Hull. It also includes teaching notebooks prepared for theatre and drama courses at Washington University and diaries Professor Carson kept of theatre and music performances he attended from 1913 to 1966, primarily in St. Louis.

Accrual 3 includes scripts of plays by Washington University students, news clipping about Professor Carson's retirement, theatre programs, and printed material.

Accrual 4 includes materials that fall under two main categories: early New Mexico history and materials relating to Carson's theatrical activities. Carson's research into New Mexico history was prompted by the fact that his great-great-grandfather, William Carr Lane, besides being one of the first St. Louis mayors, was also first governor of New Mexico, 1852-1853. The diary kept by Lane during his governorship was edited by Carson, requiring research into geography and exploration, Indian relations, and political figures of the period. The Theatrical Activities include personal material, material from his teaching at Washington University, material from Washington University's Thyrsus organization, material from his time as a playwright and director, material from Carson as an author, material from St. Louis' Little Theatre and The Players, and his research on theatre and musical performances. This also includes printed material and maps.