Senator Wilhelm is chair of the Local Government Committee and vice-chair of the Human Resources Committee. She also serves on the Commerce, Education, and Economic Growth committees, as well as the Agriculture & Natural Resources Budget.

Prior to being elected to the Senate, Mary Jo served on the Howard County Board of Supervisors. She has been a Certified Residential Appraiser since 2000 and started her own business, Wilhelm Appraisals, in June 2006. 

Mary Jo and her husband, Michael, have been married for 28 years and live in Cresco, where they are members of Immanuel Lutheran Church. They have two sons: Ben, who lives in Iowa City, and Alex, who lives in Cedar Rapids.