Roberto Saba is a historian of the nineteenth-century United States and its engagement with other parts of the world. He approaches his subjects from transnational and comparative perspectives. His research and teaching focus on capitalism, imperialism, and slavery. He is also interested in the histories of migration, popular culture, world's fairs, and exploration.   

His book—American Mirror: The United States and Brazil in the Age of Emancipation (Princeton University Press, 2021)—investigates how American and Brazilian reformers worked together to ensure that slave emancipation would advance the interests of capital. He has also published a chapter titled "The Sun Rises in the North: Brazilian Periodicals Published in the United States in the 1870s" in the edited volume
Press, Power, and Culture in Imperial Brazil (New Mexico University Press, 2021).