Reconstructionist Judaism is a Jewish movement based on the concepts developed by Rabbi Mordecai Kaplan (1881–1983) that views Judaism as a progressively evolving civilization rather than just a religion. The movement originated as a semi-organized stream within Conservative Judaism, developed between the late 1920s and the 1940s before seceding in 1955, and established a rabbinical college in 1967. Reconstructionist Judaism is recognized by many scholars as one of the five major streams of Judaism in America alongside Orthodox, Conservative, Reform, and Humanistic.

Jewish religious movements, sometimes called "denominations", include diverse groups within Judaism which have developed among Jews from ancient times. Today in the west, the most prominent divisions are between traditionalist Orthodox movements and modernist movements such as Reform Judaism originating in late 18th century Europe, Conservative originating in 19th century Europe, and other smaller ones, including the Reconstructionst and Renewal movements which emerged later in the 20th century in the United States.