Professor Greenstein started his engineering career at Brooklyn Technical High, after graduation he attending The City College of New York where he graduated with a Bachelor of Engineering (Mechanical). Upon graduation he worked for General Electric and spent two years on their Manufacturing Management Program.
While working for General Electric, he received a Master of Business Administration, from The University of Louisville and is a Professional Engineer. After leaving General Electric, he had various positions with Gould, Crouse-Hinds, Amtrak and AT&T/Lucent Technologies. He is a registered Professional Engineering (Kentucky).
At AT&T/Lucent Technologies he worked for Bell Laboratories, Corporate Education, Submarine Systems, Supply Chain Management and Network Systems. Retiring from Bell Laboratories in 2001, he accepted a position at Polytechnic Institute of NYU in Brooklyn. Currently he is the Director of The Manufacturing and Industrial Engineering Programs and responsible for the administration of the GEM and internship programs.