Sklar began his career as a reporter for the Los Angeles Times. He received a Ph.D. in the history of American civilization from Harvard University in 1965. In 1968, he signed the "Writers and Editors War Tax Protest" pledge, vowing to refuse tax payments in protest against the Vietnam War.
- F. Scott Fitzgerald: The Last Laocoon (London: Oxford University Press, 1967)
- Film: An International History of the Medium (1990)
- City Boys: Cagney, Bogart, Garfield (1992)
- Movie-Made America: A Cultural History of American Movies (1975; revised 1994)
- Silent Screens : The Decline and Transformation of the American Movie Theater (2000)
- A World History of Film (2003)