Peterson adapted his dissertation as his first book, "The Jefferson Image in the American Mind" (Oxford University Press, 1960), which won the 1961 Bancroft Prize for History. It is still hailed as a pioneering exploration of the history of American memory, which has become an increasingly important topic for historians. Peterson undertook the work to assess what history had made of Thomas Jefferson. At the end of a decade, he published a lengthy one-volume biography, "Thomas Jefferson and the New Nation" (Oxford University Press, 1970), which he considered his most important book. His 1994 "Lincoln in American Memory," was written from a similar stance as his first book on Jefferson. It was a finalist for the 1995 Pulitzer Prize for biography.