He graduated from Manhattan College, and from Cornell University with an MA, and a Ph.D. in 1971.

He taught at Yale University, University of Canterbury, University of Warwick, University of Cambridge. He is currently a Distinguished University Professor at Southern Methodist University.^[1]

• 1983-91 Royal Historical Society
• L.H.D. Honoris Causa Manhattan College
• 1982 Bancroft Prize for A People in Revolution
• 1966-71 Danforth Graduate Fellow
• 1966-67 Woodrow Wilson Fellow

• A People in Revolution: The American Revolution and Political Society in New York, 1760-1790. Johns Hopkins University Press. 1981. ISBN 9780801826252. OCLC 7551670. Reprinted as a paperback in 1989; see A People in Revolution: The American Revolution and Political Society in New York, 1760-1790. W. W. Norton. 1989. ISBN 9780393306064.
• The American Revolution. Hill & Wang. 1985. ISBN 978-0-8090-2562-6. Revised edition Macmillan, 2003 ISBN 978-0-8090-2562-6.
• Americans: A Collision of Histories. Hill & Wang. 1996. ISBN 978-0-8090-1598-6. Revised edition Macmillan, 1997, ISBN 978-0-8090-1598-6.
• Shane. British Film Institute. 1999. ISBN 978-0-85170-732-7. Co-author with Evonne von Heussen-Countryman.
• The Empire State, co-author, Cornell University Press, 2001
• Enjoy the Same Liberty: Black Americans and the Revolutionary Era. Rowman & Littlefield Publishers. 2012. ISBN 978-1-4422-0028-9.

Historians at Work, series editor edit

• What Did the Constitution Mean To Early Americans?. Bedford/St. Martin's. January 15, 1999. ISBN 978-0-312-18262-5.
• How Did American Slavery Begin?. Bedford/St. Martin's. January 15, 1999. ISBN 978-0-312-18261-8.

• https://web.archive.org/web/20100331065626/http://smu.edu/history/faculty/countryman.shtml