In 1970, he moved to the Johns Hopkins Bloomberg School of Public Health as an assistant professor.
During his tenure at UTHealth, he also helped establish the Southwest Center for Prevention Research, serving as its co-director.
He was also associate director of the Institute for Health Policy Education and Research at UTHealth during this period.
As vice president and director of the National Health Promotion Program of the Henry J. Kaiser Family Foundation from 1988 to 1991, he and his staff developed a community development strategy for grant making called the Social Reconnaissance method.
A national media campaign organized by his staff, called Project LEAN (Low-fat Eating for America Now), won awards and helped launch many of the industry-professional collaborations that have contributed to the reduction of dietary fat in the American food supply.
Returning to the United States, he was distinguished fellow/visiting scientist at the Centers for Disease Control and Prevention (CDC) from 1999 to 2004.
Since fall of 2005, Green has been adjunct professor in the Department of Epidemiology and Biostatistics at the University of California at San Francisco.