Ortiz has published and taught in the fields of African-American history, Latino Studies, the African Diaspora, Social Movement Theory, U.S. History, U.S. South, labor and documentary studies. He is the author of Emancipation Betrayed: The Hidden History of Black Organizing and White Violence from Reconstruction to the Bloody Election of 1920 (University of California Press) and coeditor of the oral history Remembering Jim Crow: African Americans Tell About Life in the Segregated South (The New Press).