The Liberal Jewish Synagogue, or LJS (Hebrew: קהל קדוש לב חדש, Qahal Kadosh Lev Chadash, "Holy Congregation New Heart"), is a house of prayer in St John's Wood, London, founded in 1911. It is the oldest and largest member of Britain's Liberal Judaism, a constituent member of the World Union for Progressive Judaism. The synagogue uses the Lev Chadash denominational prayerbook. Since its earliest days, it has had mixed-gender seating.