Mike Sullivan grew up in the Adirondack Mountains of Upstate New York, where his love of trees began. He graduated from Williams College in 1981 and the University of Michigan Law School in 1984, when he moved to San Francisco to become a corporate lawyer. In the early 1990s he joined local tree planting organization called Friends of the Urban Forest as a volunteer, later serving on the group's board of directors for 12 years and as President of the Board for several years. Sullivan served on the San Francisco Urban Forestry Council from 2003-2005, and on the City's Recreation and Park Commission from 2007-2010. He lives in San Francisco's Parnassus Heights neighborhood with his husband Paul and 9 year old son Joseph, who was born the same week the family planted the now 25 ft. soapbark tree (Quillaja saponaria) in front of the family home.