The Willie L. Brown, Jr. Papers include Assembly Bill materials, correspondence, newspaper clippings, research files, awards, books, editorial cartoons, photographs and other materials created during his years in the California State Assembly (1965-1995).

Series 1: Assembly Bill Materials, 1965-1996, includes documents pertaining to legislative bills Brown introduced or co-sponsored in the California State Assembly. Also includes materials relating to House Resolutions, Assembly Constitutional Amendments, Assembly Concurrent Resolutions, and Assembly Joint Resolutions. Assembly Bill files minimally contain government published copies of the Assembly Bills, along with amended versions, and the Legislative Council Digest related to the bill. Files may also contain committee analyses of the bills, correspondence from government officials, constituent individuals and organizations, and newspaper or magazine articles, newsletters and brochures. Brown's legislative files reflect his early efforts to support health benefits for people with AIDS, support for dentists trained in foreign schools, and civil rights issues.

Series 2: Subject Files, 1965-1995, consists of documents on a variety of topics collected by Brown's legislative staff for research purposes.

Series 3: Political Appointments, 1981-1997, spans the years that Brown served as Speaker of the Assembly. Includes documentation of Brown's political appointments to California commissions, boards, and committees. Files include a description of each body, including its responsibilities, duties and membership; correspondence relating to potential appointees; and oath statements from appointed members.

Series 4: Correspondence, 1965-1994, includes endorsement letters from Brown in support of individuals and organizations; and letters to Brown seeking his support. There is also other correspondence throughout the collection in other series.

Series 5: Awards and Recognitions, 1972-1995, consists of paper certificates presented to Brown by various organizations for his achievements as a legislator. Related files include digital files of plaques presented to Brown. Special Collections and Archives has digital images of processed plaques and ephemera.

Series 6: Ephemera, 1962-1994, consists of newspaper clippings and memorabilia, such as printed programs from events.

Series 7: Books, 1985-1999, consists of books produced by or for Brown during his tenure as Speaker of the Assembly. Also includes a bound transcript of an oral history interview with Brown recorded in 1991-1992.

Series 8: Art, 1970-1995, contains framed and unframed artistic portrayals of Brown. Mostly editorial cartoons depicting his stance on various political issues and events.

Series 9: Photographs and Sound Recordings, 1966-1997, contains photographs, negatives, and slides that provide visual documentation of Brown's legislative career. The files include his early years, his family, assembly floor action, events hosted or attended by Brown including—his major fundraisers—and individuals he interacted with, including political figures, foreign dignitaries, athletes, celebrities, and friends. Also contains sound recordings of Brown and news programs. Formats include audio cassettes (bulk), open reel ¼-inch tape, and micro-cassettes.