Crowley joined the Australian Labor Party in 1974 as the president of the Mitcham branch, and later of the Unley branch. She was also a member of the ALP's Women's Policy Committee from 1979 to 1983 and the SA Health Platform Committee from 1981 to 1983. Crowley entered the Senate in 1983, the first woman from the Australian Labor Party in South Australia to do so. During her term in the Senate, she held two ministerial positions: Minister for Family Services from 24 March 1993 to 11 March 1996, and Minister Assisting the Prime Minister for the Status of Women from 24 March to 23 December 1993. The former was a junior ministry within the Department of Health, Housing, Local Government and Community Services.