Ermarth received a BA in History from Wittenberg University in Springfield, Ohio, in 1961, and an MA in Soviet Studies from Harvard University in 1963. He speaks German and Russian.
In 1965 he joined Radio Free Europe as a Soviet affairs analyst, working in Munich, West Germany. He then held a range of posts in the CIA and the Rand Corporation. He officially retired from the CIA on 1 October 1998. Since 2002 he has been Director of National Security Programs at the Nixon Center. He is also a part-time senior analyst for the Strategies Group at Science Applications International Corporation.
Deep political connections
He is an attendee of Le Cercle.