Stephens joined the ALP as a result of the dismissal of the Whitlam Government in 1975, during which she travelled to Canberra to attend protests. She was the first member of her family to join a political party. Stephens served on the Australian Labor Party National Executive and the national executive of the Labor Women's Network. She was president of the Australian Labor Party (New South Wales Branch) from 2002 to 2006, the first woman to hold the position.