Richard S. Levy, who grew up to become one of the nation’s foremost experts on the history of antisemitism, first experienced it as a young boy.

He was about 5 when a nun at the Catholic school he was attending shushed noisy students with a comment that prompted his parents to pull him out of the school the next day.

“One of the nuns said, ‘I want you to be quiet. The last one talking is a Jew,’ ” his brother David Levy said.

At 11, “One of the kids in class was having a birthday,” said his wife Linnea. “The mother talked to her son about inviting all the kids who were standing around playing baseball. But Richard heard her whisper to her son, ‘Not the Jew.’ He told me about that story and how it hurt.”

Mr. Levy, a history professor at the University of Illinois at Chicago who taught for nearly half a century on the Holocaust, antisemitism and German history, died of prostate cancer June 23 at his Lake View home. He was 81.

After graduating from Morton High School in Cicero, he got his bachelor’s degree from the University of Chicago and a master’s and doctorate at Yale University, then taught at the University of Massachusetts Amherst.

His dissertation became the ground-breaking 1975 book “The Downfall of the Anti-Semitic Political Parties in Imperial Germany.”

“There was a tendency to say antisemitism was in the air of this country,” said Peter Hayes, a retired Northwestern University history professor. “Richard said ‘No, it’s more complicated.’ He makes the argument that there were more effective structures to fight antisemitism before 1918” in Germany.

In addition to many articles, translations and contributions to books, Mr. Levy edited the two-volume 2005 book “Antisemitism: A Historical Encyclopedia of Prejudice and Persecution.”

“It was a huge international undertaking, where he got a large number of very important professors and scholars to contribute,” said Kevin M. Schultz, who chairs the UIC history department and said the encyclopedia “has sort of become the first stop for anyone wanting to study the history of antisemitism.”