Betty Miller Unterberger was born in Glasgow, Scotland, and grew up in the USA. In 1943, she earned a bachelor's degree from Syracuse University, and then a master's degree in history from Radcliffe College. From historian Thomas A. Bailey, a visiting scholar from Stanford University, she learned about the American troops sent to Siberia in Russia to fight in the civil war that followed the Russian Revolution of 1917. She earned a Ph.D. at Duke University in 1950 with a dissertation on the subject that became the basis for her first book, America's Siberian Expedition, 1918-1920: A Study of National Policy (1956). Most of her subsequent publications focused on international diplomacy and history. From 1948 to 1950, she taught at East Carolina University in Greenville, North Carolina, and then became an associate professor of history and the director of the Liberal Arts Center for Adults at Whittier College in California. She also taught at California State University in Fullerton, where she became chairman of the graduate studies division. In 1968, she became the first woman on the faculty of Texas A&M University, where her husband, Robert R. Unterberger was a professor of geophysics. From the late 1980s, she was a frequent visiting professor, teaching at the University of California, Irvine, Peking University, and Charles University in Prague, among others. In 1991, she was appointed Patricia and Bookman Peters Professor of History at Texas A&M, and in 2000 was elevated to Regents Professor. In 1986, she was elected the first woman president of the Society for Historians of American Foreign Relations. In 2004, the society established the Betty M. Unterberger Dissertation Prize in her honor. She was an advocate of the Freedom of Information Act and served on the CIA's Advisory Committee for Access to Documents and Open Information.