Jonathan Greenblatt, the chief executive of the Anti-Defamation League, said in a recent interview: “Jews know what it means to be identified and tagged, to be registered and pulled aside. It evokes very deep emotions in the Jewish community.”

Mr. Greenblatt received a standing ovation when he declared at his organization’s conference in Manhattan last month that if Muslims were ever forced to register, “that is the day that this proud Jew will register as a Muslim.”

“All of us have heard the story of the Danish king who said if his country’s Jews had to wear a gold star,” he said, “all of Denmark would, too.”

Nearly 500 Muslim and Jewish women, many wearing head scarves and skullcaps, gathered on Sunday at Drew University in Madison, N.J., in what organizers said was the largest such meeting ever held in the United States. It was the third annual conference of the Sisterhood of Salaam Shalom, a grass-roots group that now claims 50 chapters in more than 20 states. The first conference two years ago drew only 100 people.

The women spread out inside an enormous sports complex and met in clusters to study sacred texts on the racquetball courts, practice self-defense techniques in the dance studio and, in the bleachers, discuss how to talk to friends whose impression of Islam had been shaped entirely by news of terrorist attacks.

Over lunch and in the hallways, they traded stories about the latest ugly outbreaks back home: a brick thrown through the window of a Muslim-owned restaurant in Kansas, apartments of Muslim families in Virginia hit with eggs and graffiti, swastikas scrawled on synagogues and in a playground in New York. Sisterhood chapters keep track of the incidents on their Facebook pages and other social media.

“Ignorance is one of the key triggers of hate,” said Sheryl Olitzky, the group’s executive director, in her opening remarks. “We need to show the world that we are Americans. We are here because we love each other and we’re overcoming hate.”