Marilyn Field-Marsham practiced commercial law for over 20 years at Osler, Hoskin and Harcourt in Toronto. She was a director of AIM Canada Fund Inc., AIM Global Fund Inc. and AIM Trimark Funds Advisory Board.
She has served on the boards of several not-for-profit and public companies over the past 15 years and also on their governance, human resources, finance and audit and investment committees. She is the chair of the Mount Pleasant Group of Cemeteries in Toronto and the incoming chair of the governance committee of the Mount Pleasant Memorial Services. She served as a committee chair at the American Bar Association. She served on the editorial board to the Intellectual Property Law Quarterly, Corporate Lawyer Series, Federated Press. She is also author of numerous articles on developments in legislation and jurisprudence. She has been actively involved with Massey College University of Toronto, Toronto Trees and Parks Foundation, and supported Trails Youth Initiative. She is currently a volunteer for the aboriginal governance and strategic planning projects, CESO (Canadian Executive Services Organization).