Conservative Judaism (known as Masorti Judaism outside North America) is a Jewish religious movement, that regards the authority of Jewish law and tradition as emanating primarily from the assent of the people through the generations, more than from divine revelation. It therefore views Jewish law, or halakha, as both binding and subject to historical development. The Conservative rabbinate employs modern historical-critical research, rather than only traditional methods and sources, and lends great weight to its constituency, when determining its stance on matters of practice. The movement considers its approach as the authentic and most appropriate continuation of halakhic discourse, maintaining both fealty to received forms and flexibility in their interpretation. It also eschews strict theological definitions, lacking a consensus in matters of faith and allowing great pluralism.

While regarding itself as the heir of Rabbi Zecharias Frankel's 19th-century Positive-Historical School in Europe, Conservative Judaism fully institutionalized only in the United States during the mid-20th century. Its largest center today is in North America, where its main congregational arm is the United Synagogue of Conservative Judaism, and the New York–based Jewish Theological Seminary of America operates as its largest rabbinic seminary. Globally, affiliated communities are united within the umbrella organization Masorti Olami. Conservative Judaism is the third-largest Jewish religious movement worldwide, estimated to represent close to 1.1 million people, including over 600,000 registered adult congregants and many non-member identifiers.