Chantal Mancini's involvement with unions spans nearly two decades. She is a secondary school teacher and former local president of the Ontario Secondary School Teachers' Federation, District 21 (Hamilton-Wentworth), a position she held for ten years. Chantal's union experience includes collective bargaining, contract maintenance, grievances and arbitration, worker representation, health and safety, political action, and involvement with both the Hamilton and larger labour community. 

She is currently a delegate to the Hamilton and District Labour Council for CUPE 3906, a member of the Hamilton and District Labour Council executive, and a member of the Board of Directors for the Workers' Arts and Heritage Centre in Hamilton. 

Her interests include education sector collective bargaining, public sector unionism, and gender and work.