James Loeffler is the Felix Posen Professor of Modern Jewish History at Johns Hopkins University, where he serves as Director of the Leonard and Helen R. Stulman Program in Jewish Studies. He is also Kogod Senior Research Fellow at the Shalom Hartman Institute of North America, where he previously led the antisemitism research seminar. He writes widely on modern Jewish history from antisemitism to Zionism, with a focus on the overlooked ties between the Jewish past and the global present in politics, law, and culture.

A graduate of Harvard and Columbia Universities, he pursued postgraduate studies in Israel at the Pardes Institute and the Hebrew University of Jerusalem. He went on to serve as Sound Archivist at the YIVO Institute for Jewish Research. His scholarly work has been supported by fellowships from the Dorot Foundation, the Wexner Foundation, the Fulbright Fellowship, the American Council of Learned Societies, and the Mellon Foundation. He has served as Dean’s Visiting Scholar at Georgetown University Law Center, Kluge Fellow at the Library of Congress, and Robert A. Savitt Fellow at the United States Holocaust Memorial Museum. He is a permanent Fellow of the American Academy for Jewish Research and immediate past editor of the Association for Jewish Studies Review.

He is the author of Exceptional Hatred: Antisemitism and the Fight over Free Speech in Modern America, published by Metropolitan Books, an imprint of Henry Holt & Company. His 2018 book Rooted Cosmopolitans: Jews and Human Rights in the Twentieth Century won the American Historical Association’s 2019 Dorothy Rosenberg Prize for best book in the field of Jewish history and the Association for Jewish Studies 2019 Jordan Schnitzer Prize for best book in the field of modern Jewish history.

His other books include The Most Musical Nation: Jews and Culture in the Late Russian Empire (Yale, 2010), which won eight major awards and honors, including from the Association for Jewish Studies, the Sami Rohr Prize, and the ASCAP foundation and two co-edited volumes, A Jew in the Street: New Perspectives on European Jewish History (Wayne State University Press, 2024) and The Law of Strangers: Jewish Lawyers and International Law in the Twentieth Century (Cambridge, 2019). His other writings include essays on East European Jewish history, the antisemitism of Richard Wagner and Frederic Chopin, the tangled roots of Israeli music, and international law. His writings have appeared in The Atlantic, The New York Times, The Washington Post, The Wall Street Journal, Tablet,  Haaretz, The New Republic and Newsweek, among other places. In 2025 he received the Rockower Press Award for Excellence in Writing about Antisemitism.

He is currently at work on a biography of Raphael Lemkin (1900-1959), the Polish Jewish lawyer who coined the term “genocide.” He also curates The Lemkin Project, a digital archive of new translations of the forgotten Hebrew, Yiddish, and Polish writings of Lemkin. Other projects include a collaborative research study of Avraham Zvi Idelsohn (1882-1938) the Jewish musician and scholar who created “Hava Nagila,” and a critical study on religion and international law based on the writings of Rabbi Hayyim Hirschensohn (1857-1935), the first major Ashkenazi Orthodox rabbi to write about Judaism and international law.

A trained pianist and musicologist, for ten years he curated a concert series devoted to Jewish composers at the Kennedy Center. He has consulted to National Public Radio, Carnegie Hall, the Warsaw Polin Museum, and the YIVO Institute for Jewish Research, where he previously worked as Sound Archivist. He also contributed the liner notes to the Grammy-nominated album The Zemiros Project (Traditional Crossroads, 2000). He currently co-directs The Idelsohn Project with Professor Edwin Seroussi.

From 2006 to 2023, Loeffler taught at the University of Virginia, where he was the inaugural Jay Berkowitz Professor of Jewish History and served as Ida and Nathan Kolodiz Director of Jewish Studies.

He lives in Washington, DC with his wife and children.