Sweet has served in a variety of professional leadership positions. At UW-Madison, he directed the African Studies Program (2012-2013), chaired the Department of History (2013-2016), and chaired the Department of Spanish and Portuguese (2017-2020). He is a book series editor for the University of Wisconsin Press. He also sat on the editorial boards of Luso-Brazilian Review, The Americas, andJournal of Africana Religions. Additionally, he serves on the advisory board for “Save or Enslave: Religion and Slavery in the Portuguese Seaborne Empire, 1452–1741,” a research project based at the University of Coimbra in Portugal.

He has served in various professional capacities for the American Historical Assocuiation (AHA). He was the president of the AHA from 2021 to 2023, the largest organization of its kind in the world, and the oldest professional organization of historians in the United States. As president, he penned monthly columns in AHA’s news magazine, Perspectives on History. His columns include: “Grief, Goodness, and History” (December 2022); “Our Letter-Writing Culture” (October 2022); “Is History History?” (September 2022); “Professor Coach” (May 2022); “Finding our Roots” (April 2022); “March Madness” (March 2022); “Diffusion as Dilution?” (February 2022); and “From Inclusive Public Schools to Divisive Concepts” (January 2022).