As a historian, she specialized in the history of Eastern Europe, especially the Russian Empire and of the Soviet Union.
She received advanced degrees in Russian history and literature from Indiana University at Bloomington.
Whittaker was a Fulbright Scholar and received research grants from—among others—the Harriman and Kennan Institutes, as well as the Rockefeller Foundation.
From 1999 to 2000 she was a visiting fellow at the Slavic Research Center of Hokkaido University in Japan.
From October 2003 to May 2004 she co-curated a museum exhibit entitled Russia Engages the World, 1453-1825 at the New York Public Library.