Reconstructionist Judaism is a Jewish movement based on the concepts developed by Rabbi Mordecai Kaplan (1881–1983)—namely, that Judaism is 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.