He has been at NSU since 2004, and in 2005 founded NSU Theatre, the producing ensemble for theatre and musical theatre events at NSU. Duncan is a graduate of Chicago's Second City Conservatory. He has taught theatre courses at Virginia Commonwealth University, Joliet Junior College, University of Central Arkansas, and Wesleyan College. Duncan is actively involved in and regularly presents at the Southeastern Theatre Conference, Florida Thespian Conference, Association for Theatre in Higher Education, and the Florida Theatre Conference (former Board Member). Mark is an Associate Member of Stage Directors and Choreographers Society (SDC).