She is best known for her position as the associate director for Science in the
White House Office of Science and Technology Policy (confirmed by the US Senate) during the Clinton Administration. She also served as
President of the American Association for the Advancement of Science in 1999. In addition, she has been President of the North American Association for the Study of Obesity (NAASO)—now the Obesity Society; and also President of the American Society of Clinical Nutrition. Formerly an adjunct professor of Public Health and Nutrition at the
University of California, Berkeley, she currently holds an appointment as a Distinguished Professor Emerita of Nutrition and Internal Medicine at the
University of California, Davis. She held various positions in the
University of California system: as Provost and Senior Vice President for Academic Affairs, University of California Office of the President; Chancellor of
University of California, Santa Cruz; and Dean of Graduate Studies and Vice Provost at University of California, Davis. During her time at chancellor, she oversaw the opening of the University of California system's first new residential college in 30 years. Her tenure oversaw the hiring of 250 new faculty members and academic programs were expanded by 52 percent. In 2005, the University of California found that Dr. Greenwood had violated its conflict of interest rules related to a management position created for a colleague with whom she co-owned a rental property. The university found no evidence of improper conduct in a second allegation that she influenced a position held by her son at UC Merced, concluding no pattern of impropriety or ethics violations in regard to both matters that were thoroughly investigated. The university accepted Dr. Greenwood's resignation from the position and affirmed her return to the tenured professorship she formerly held at the University of California, Davis. Greenwood became the President of the
University of Hawaiʻi in 2009 and was the first woman to hold the position. During her tenure, she oversaw several major projects including the University of Hawaiʻi Cancer Center, the new
University of Hawaiʻi at West Oʻahu campus, the
University of Hawaiʻi at Hilo Hawaiian Language and Culture building, the
Windward Community College Learning Center, the
Maui Community College Science and Technology Center, the
Kauaʻi Community College Campus Center project, the
University of Hawaiʻi at Mānoa Campus Center and a new Information Technology Building. On May 6, 2013, Greenwood announced her retirement from the University of Hawaiʻi as president. She is a member of the
Institute of Medicine in the
National Academy of Sciences, and a fellow of the American Academy of Arts and Sciences. ==Awards and fellowships==