Thompson is a Madison native, and graduated from Madison East High School in 1968. She was one of ten children; her father was a painter for the University of Wisconsin–Madison, and her mother was a janitor for the Department of Administration. She worked in the travel industry for 27 years, and lived in Waunakee. Thompson was hired in 2001 into the civil service by the state Department of Administration, when Republican Scott McCallum was Governor. Thompson was described as "apolitical", hard-working, and "intensely private".