The Sonja Larsen papers date from 1977 to 1982 and measure 12 linear inches. The papers are arranged in five series: Political campaigns, Political career, Post-political career, Photographs, and Artifacts.

The Political campaigns series comprises Larsen's campaigns for state representative and her campaign for mayor of Ottumwa, dating from 1977-1981. This series includes campaign analysis, brochures and literature, correspondence, campaign finance documents, the state Republican campaign handbook, newspaper clippings, documents relating to publicity efforts, speeches, and lists of campaign volunteers and potential donors.

The Political career series spans Larsen's tenure as an elected official, dating from 1977-1982. This series includes literature relating to Larsen's position on proposed legislation, particularlyon issues such as abortion, education, creationism, the ERA, and conservation of natural resources. The series also comprises constituent contact records, the text of proposed legislation for which Larsen was a sponsor, a legislative handbook, newsletters, newspaper clippings, press releases and speeches.

The Post-political career series dates from 1981-1982 and includes correspondence relating to Larsen's electoral defeat in 1980 and continued involvement in politics through her editorship of the Wapello County Republican News, as well as newspaper clippings.

The Photographs series dates from the late 1970s and consists primarily of campaign photographs and shots of Larsen at speaking engagements.

The Artifacts series includes campaign materials, nametags, and a guestbook from a 1978 fundraiser.