Helen L. Koss was born Helen Koss in New York City, New York, on June 3, 1922. She grew up in Ellenville, NY. She graduated from Bennington College in 1942 and moved to Washington, D.C. where she worked for the U.S. Department of Agriculture. She moved to Montgomery County in 1951 with her husband Howard. From 1963 to 1967, she served as president of the League of Women Voters of Maryland. During this time, the League devoted most of its efforts toward the civil rights movement in the form of advocating public accommodations for all. She was elected to the Maryland House of Delegates in 1971, and served until her retirement in 1987. She was appointed to chair the Constitution and Administrative Law Committee in 1979, marking the first time a woman held the chair of a permanent committee in Maryland.
During her tenure in the Maryland House of Delegates, Helen L. Koss focused most of her efforts on campaign reform and eliminating gender discrimination in the credit, housing and insurance industries. She also proposed numerous bills which aimed at improving the plight of divorced women. Her greatest achievement was the Displaced Homemakers Bill, a bill which established a center for training women in skills which would enable them to work outside of the home.
In 1993, Governor Parris Glendening appointed Koss to the state election board, where she served until 2003. She passed away on September 28, 2008.