Ida Mett (1901–1973) was a Belarusian Jewish anarcho-syndicalist, physician and writer. Following her experiences in the Russian Revolution, she fled into exile in France, where she collaborated with other exiled revolutionary anarchists on the Delo Truda magazine and the constitution of platformism. She then went on to participate in the anarcho-syndicalist movements in Belgium, Spain and France, before repression by the fascist Vichy regime forced her to cease her activities. She spent the final decades of her life working as a nurse and publishing history books.

Platformism is an anarchist organizational theory that aims to create a tightly-coordinated anarchist federation. Its main features include a common tactical line, a unified political policy and a commitment to collective responsibility.