[11] It was founded in late September 1913 by the Independent Order of B'nai B'rith, a Jewish service organization, in the wake of the contentious murder conviction of Leo Frank.

[25] One of the ADL's early campaigns occurred in the 1920s when it organized a media effort and consumer boycott against The Dearborn Independent, a publication published by American automobile industrialist Henry Ford.

[32] During the 1930s, ADL, along with the AJC, coordinated American Jewish groups across the country in monitoring the activities of the German-American Bund and its pro-Nazi, nativist allies in the United States.

In their final reports to Congress, both committees found that the sudden rise in political antisemitism in the United States during the decade was due, in part, to the German government's support of these domestic groups.

The ADL requested its members avoid public confrontation, instead directing them to send letters to the media and advertising companies that included antisemitic or racist references in screening copies of their books and movies.

The report came in the wake of the trial of Tom Metzger, a white supremacist leader found guilty of inciting a murder via his public access TV station.

The national chair of the governing board of directors is Esta Gordon Epstein; elected in late 2018 for a three-year term, she is the second woman to hold the organization's top volunteer leadership post.

It found that the majority of surveyed players experienced severe harassment of some kind, and the ADL recommended increased content moderation from game companies and governments.

[76] In 2020, ADL joined with the NAACP, Color of Change, LULAC, Free Press, the National Hispanic Media Coalition and other organizations in the Stop Hate For Profit campaign.

[90] In November 2022, ADL acquired JLens, a pro-Israel advocacy group started in 2012 which campaigns against incentives for economic disengagement with Israel in environmental, social, and corporate governance (ESG) investing guidelines.

[111] In 2010, ADL published a list of the "ten leading organizations responsible for maligning Israel in the US," which has included ANSWER, the International Solidarity Movement, and Jewish Voice for Peace for its call for BDS.

[114] ADL expressed concern over Israeli legislative proposals requiring that NGOs publicize if they receive funding primarily from non-Israeli governments, a bill mostly opposed by centrist and left-wing and supported by right-wing Jewish American groups.

[115] In 2022, the ADL criticized the government formed by Benjamin Netanyahu in his sixth term, which included representatives from the far-right Otzma Yehudit and Religious Zionist Party, and their leaders, Itamar Ben-Gvir and Bezalel Smotrich.

[123] Former staff told The Daily Beast in 2023 of dissent within the ADL over the increasing equation of anti-Zionism and antisemitism, and over Greenblatt's calls for bans and investigations of pro-Palestinian organizations that he alleged had supported terrorist groups.

[35] Reviewing Forster and Epstein's work in 1974 for the neoconservative magazine Commentary, Earl Raab, founding director of the Nathan Perlmutter Institute for Jewish Advocacy at Brandeis University, agreed that a "new anti-Semitism" was indeed emerging in America in the form of opposition to the supposed collective rights of the Jewish people, but Raab criticized Forster and Epstein for "stretch[ing] the word in practice to mean anti-Israel bias in general".

[20] Allan Brownfeld, a columnist with The Lincoln Review, wrote in the Journal of Palestine Studies 1987 that Forster and Epstein's new definition of antisemitism trivialized the concept by turning it into "a form of political blackmail" and "a weapon with which to silence any criticism of either Israel or US policy in the Middle East,"[133] while Edward S. Shapiro, in A Time for Healing: American Jewry Since World War II, has written that, "Forster and Epstein implied that the new antisemitism was the inability of Gentiles to love Jews and Israel enough.

Regarding the latter, Associate Regional Director Nancy Appel stated that while good people could disagree on the issue of circumcision, it was unacceptable to use antisemitic imagery within the debate.

[147] In 2010, during a hearing for Florida House Bill 11 (Crimes Against Homeless Persons), which was to revise the list of offenses judged to be hate crimes in Florida by adding a person's homeless status,[148] the League lobbied against the bill, which subsequently passed in the House by a vote of 80 to 28 and was sent to the Senate,[149] taking the position that adding more categories to the list would dilute the effectiveness of the law, which already includes race, religion, sexual orientation, disability, and age.

[150] ADL supports Comprehensive and DREAM Act legislation that would provide conditional permanent residency to certain undocumented immigrants of good moral character who graduate from US high schools, arrived in the United States as minors, and lived in the country continuously for at least five years prior to the bill's enactment.

The groups' leaders said they were concerned about the possibility of protests because Mandela had embraced Palestine Liberation Organization Chairman Yasser Arafat and Libyan president Muammar Gaddafi.

"[166] In his 2010 book The Unspoken Alliance, Sasha Polakow-Suransky criticized the ADL for hiring the private spy Roy Bullock to collect information on the anti-apartheid movement in the United States.

[67] Graduate student and activist Emmaia Gelman wrote in the Boston Review in 2019 that the ADL has conducted a "vigorous, and successful campaign, alongside AIPAC, specifically to characterize Arab American political organizing as dual loyalty."

[196][197][198] In Watertown, Massachusetts, which has a significant Armenian population, the town council in early August 2007 decided unanimously to withdraw from ADL's "No Place for Hate" anti-discrimination campaign over the issue.

[225] Two years later, in 2024, the ADL asserted that Students for Justice in Palestine (SJP) had violated federal law concerning material support for Hamas, a statement that both The Nation and The Intercept observed was made without any evidence.

[226][227] The SJP responded by stating that "rather than combating [authoritarianism and racism] and organizing for genuine social justice, the ADL has leveraged Islamophobia, anti-Arab sentiment, and conservatism to delegitimize the movement for Palestine liberation".

[228] The ADL's claims against the SJP were criticized by the ACLU which contended they "chill speech, foster an atmosphere of mutual suspicion, and betray the spirit of free inquiry".

Notable signatories included the Democratic Socialists of America, Movement for Black Lives, Jewish Voice for Peace, Center for Constitutional Rights, and Council on American–Islamic Relations.

[240][238] James Loeffler of Johns Hopkins University, a professor of modern Jewish history, commented that the English Wikipedia's decision was a "significant hit" to the credibility of the ADL.

[238] Dov Waxman, professor of Israel Studies, said that if "Wikipedia and other sources and the journalists start ignoring the ADL's data, it becomes a real issue for Jewish Americans who are understandably concerned about the rise of antisemitism".

[238] After the second inauguration of Donald Trump, businessman Elon Musk gave a speech in which he twice put his hand over his chest before raising his arm in a manner similar to the Nazi salute.