The collection deals primarily with the professional activities of Olin C. Wilson, who was most active from the mid-1930s into the 1980s. Wilson corresponded frequently with astronomers from a variety of universities in the United States and abroad, and the collection is representative of the deeply international and collaborative nature of astronomical and astrophysical research in the second half of the twentieth century. It also contains valuable and insightful material related to the schism between Mount Wilson and CalTech in the 1970s and 1980s, and the near-demise of Mount Wilson during that decade.

The collection includes correspondence with such astronomers as Walter Sydney Adams, Bernard William Bopp, Ira Sprague Bowen, Lawrence H. Aller, Robert Paul Kraft, and many other individuals, as well as considerable correspondence with the American Astronomical Society, the Astronomical Society of the Pacific, the Carnegie Institution of Washington, and other organizations.