The Campaign Against Antisemitism (CAA) is a UK-based charity established in early August 2014 as a grassroots volunteer-led initiative by members of Britain's Anglo-Jewish community, in response to a sharp rise in antisemitic incidents during the 2014 Israel-Gaza conflict. Co-founded by Joseph Cohen, with other early figures including Nathan Hopstein (original founder and former Director of Organisation and Finance), it was registered as a Charitable Incorporated Organisation (CIO) with the Charity Commission for England and Wales on 2015-10-01 under number 1163790. The current Chief Executive is Gideon Falter, who has also served as Chairman. Its activities include litigation against antisemites, awareness campaigns, rallies (e.g., the 2023 March Against Antisemitism with 50,000-100,000 attendees), polling (Antisemitism Barometer), crime audits, and pushing for adoption of the IHRA definition of antisemitism. The CAA has pursued private prosecutions leading to convictions, such as Alison Chabloz for Holocaust denial songs in 2018 and Tahra Ahmed in 2021-2022, and was praised by UK Home Secretary Theresa May in January 2015. However, the organization has faced controversy for alleged political partisanship and conflating criticism of Israel with antisemitism.