She came from a working-class background in Morozzo, Cuneo, and studied in Cuneo and Turin, where she began her political career with the Communist Party, becoming a deputy in 1987. Later she was Director of the Communist Youth League, a regional councillor and responsible for women in the local party federation.
Following the dissolution of the Communist Party in 1991, she joined the Democratic Party of the Left, and then the Democrats of the Left, as a deputy in 1992-2001.
Fom May 1996 to October 1998 she was Minister of Social Affairs (Solidarietà Sociale) in the first Prodi, and then the D'Alema (1998–2000) and Amato (2000–2001) governments.
In 2000 she unsuccessfully ran for President of Piedmont, and was elected a senator for Piedmont in 2006. She then became Minister of Health in the second Prodi government (2006-8). Following the fall of Prodi, she was elected to the Chamber of Deputies in April 2008 as a member of the center-left Democratic Party.
Her name is attached to the 1998 immigration act known as Legge Turco-Napolitano (L. 40/98).