Smallwood is an Associate Professor of History and affiliated Associate Professor of American Ethnic Studies. She is an expert on slavery in the Atlantic World (specifically in the early modern period) and her research and teaching focuses on early modern histories of slavery, colonialism, and race, with particular emphasis on precolonial Africa, the transatlantic slave trade, and African diasporas in the Americas. In 2008 she won the Frederick Douglass Book Prize for the best book written in English on slavery or abolition for her work Saltwater Slavery: A Middle Passage from Africa to American Diaspora (Harvard University Press). This book examines the transatlantic slave trade and the relationships between Africa and the New World. In addition to exploring these themes in her research Smallwood is also a passionate advocate for racial justice and has spearheaded several university events in reaction to contemporary incidences that highlight the ongoing issues surrounding race, racism and injustice in America. In 2015 she co-organized a one day teach in "Ferguson and Beyond: Race, State Violence, and Activist Agendas for Social Justice in the 21st Century," following the tragic events in that community.