ALAN M. KRAUT is University Professor of History at American University, a nonresident Fellow of the Migration Policy Institute, and president of the Organization of American Historians. He is the author of "The Huddled Masses: The Immigrant in American Society, 1880-1921"; "Silent Travelers: Germs, Genes, and the "Immigrant Menace""; "Goldberger's War: The Life and Work of a Public Health"" Crusader"; and coauthor of "Covenant of Care: Newark Beth Israel and the Jewish Hospital in America "(Rutgers University Press).DAVID A. GERBER is Distinguished Professor of History Emeritus at the University of Buffalo where he continues to teach and assist in directing the Center for Disability Studies. He is the author of "American Immigration: A Very Short Introduction" and "Authors of Their Lives: The Personal Correspondence of British Immigrants to North America in the Nineteenth Century."