The papers consist primarily of David Lewis's writings and extensive correspondence with other philosophers and scholars. There are approximately sixteen thousand pages of Lewis's correspondence, both incoming and outgoing. Significant amounts of correspondence with David M. Armstrong, J. J. C. Smart, Frank Jackson, W. V. Quine, D. H. Mellor, M. J. Cresswell, Allen Hazen, and John Bigelow are included. Lewis's letters document lively philosophical debates and reflect the development of his thought across more than four decades. Lewis's writings include drafts of published articles and books, often along with publishing correspondence, reviews, notes, and marked copies of books related to each publication, including for his books Convention (1969), Counterfactuals (1973), On the Plurality of Worlds (1986), and Parts of Classes (1991), as well as for his collected works. A smaller amount of similar materials pertaining to his reviews and unpublished or posthumously published writings is also present, as are some of his undergraduate and graduate student papers and course materials and his research files and reports from his time as a researcher at the Hudson Institute in the 1960s. Several dozen digital prints of scanned photographs of David Lewis are also present, including portraits and group shots with friends and fellow philosophers, as well as a group of photocopied materials on David Lewis maintained by David M. Armstrong. Later additions include similar material, as well as academic and administrative files; papers of Stephanie R. Lewis, a philosopher who was married to David Lewis; family papers; and digital and audiovisual materials.