She was a professor of political science at the University of Wisconsin–Madison from 1953 until 1984, and from 1974 onwards she held the Oscar Rennebohm Chair for Public Administration.
[1][7] In 1968, Penniman founded the Center for the Study of Public Policy and Administration at the University of Wisconsin–Madison, and served as its first director.
[3][11][12] Penniman published several books and articles on the topics of taxation policy and public finance, especially in the state of Wisconsin.
[18][19] However, she continued to publish well after her retirement; she was a co-author of the 1999 book Madison, An Administration History of Wisconsin's Capital City 1929-79.
[18][8] Penniman has been consistently described as one of the founding figures in the study of political science at the University of Wisconsin–Madison and in the American midwest generally, as well as being an important mentor to generations of students.
[3][9] The La Follette School has called Penniman a "nationally prominent scholar of taxation and public finance".