The Lower East Side Conservancy, also known as The Lower East Side Jewish Conservancy (LESJC), is an educational and advocacy organization, created in 1998 to preserve the synagogues and cultural heritage of the Lower East Side, America's most famous immigrant neighborhood, and present them to the public. Through the organization's efforts, many have been designated as historic landmarks, and have been listed on New York State and National Registers. In 2000, the Conservancy assisted in designating a 32 – block area as a historic district.
Their mission is accomplished through quality touring programs, both private, public, and educational, which showcase the Lower East Side's landmarks, history and people. As the only non-profit organization dedicated solely to the historic preservation of the Lower East Side's sacred sites, the Conservancy has formed relationships with the leaders of all of the synagogues remaining in this iconic immigrant neighborhood.
In addition to the Lower East Side, the LESJC provides tours of other New York neighborhoods of Jewish importance, such as Jewish Harlem, the Upper West Side, and Williamsburg, Brooklyn.
The conservancy aimed to transform the old Beth Hamedrash Hagadol into a visitors center for the Lower East Side with educational programs and gallery space, but the building was destroyed in 2017 with a fire, and was torn down in 2019.