One of the most crucial sources for divulging knowledge about the nature of God and his relationship with his creation are the various names by which God is identified throughout the Hebrew Bible and the rabbinic corpus. This chapter examines those names, especially the Tetragrammaton, based on God’s revelation to Moses recorded in Exodus of the name “I will be who I will be.” Close readings of the biblical narratives as interpreted by all the Jewish intellectual traditions, including rabbinic/midrashic, rationalist/philosophical, and kabbalistic/mystical, reveal a God of “becoming” rather than the philosophical God of “being.” The encounter and dialogue, between Moses and God, out of which the name emerges is the moment that transformatively envisages all future divine–human encounters.