On January 14, 1987, Petzold became a Maryland State Delegate for the 19th District of Montgomery County. Petzold was a Democratic delegate. During her time in the House of Delegates, she was active on issues of drug and alcohol abuse, civil rights, fair housing, education, health care, and transportation. She served on many committees during her time in office, including the Judiciary Committee (1992-2007), and chaired the Special Committee on Drug and Alcohol Abuse (2006-2007). Petzold was the president of the Women's Legislative Network from 2004 to 2005. Petzold ended her career as state delegate on January 10, 2007.
