Mark has ventured in professional planning for close to 50 years in the private and public sectors. He specializes in the field of land use planning and environmental policies. He has undertaken planning and environmental studies for public and private sector clients. 
He is President of Mark L. Dorfman, Planner Inc., in Waterloo. Mark served as CIP President from 1974 to 1976.  He was on the Board of Ontario Nature from 1995 to 2004 and served as President from 2000 to 2002.  He was on the Board of Nature Canada from 2003 to 2014, and served as Chair from 2005 to 2008 and Past Chair to 2013. 
He is the author of several published papers and has delivered papers at various conferences and workshops. In the past, he served as an Adjunct Professor in the School of Planning at the University of Waterloo.  Marks lives in and practices from Waterloo.