Mary Lewis specializes in Modern French and European social, legal, imperial, and political history. Her current research interests center around international and imperial history, with particular attention paid to the the connections between international relations and social or economic life.  She has taught courses on comparative empires, the Modern Mediterranean, Modern France and its Colonial Empire, European capitalism, and nation- and state-building in the modern era, as well as graduate seminars on method. 

Her most recent book, Divided Rule: Sovereignty and Empire in French Tunisia, 1881-1938  was published by the University of California Press in October 2013.  Based on archival research in four countries, Divided Rule uncovers important links between international power politics and everyday matters of rights, identity and resistance to colonial authority, while reinterpreting the whole arc of French rule in Tunisia from the 1880s to the mid-20th century.  Her previous book, The Boundaries of the Republic: Migrant Rights and the Limits of Universalism in France  (Stanford University Press, 2007), was a co-winner of the 2008 James Willard Hurst Prize awarded by the Law and Society Association for the best book in socio-legal history. In 2015-16, she was a Frederick Burkhardt Fellow at the Radcliffe Institute, where she begins work on a new book project, "The First French Decolonization:  A New History of 19th-century Empire," which addresses the reordering of France's overseas engagements after the sale of Louisiana and the loss of Saint-Domingue/Haiti.   In 2015, Lewis was also awarded a John Simon Guggenheim Memorial Foundation Fellowship, and Harvard named her a Walter Channing Cabot Fellow in recognition of her contributions to her field of history.   

Lewis was was co-president of the Society for French Historical Studies in 2012-13.