Why is it that in most years, but not every year, Western Christians--both Catholic and Protestant--celebrate Easter at least one week before Eastern (Orthodox) Christians? Furthermore, since the Bible portrays the resurrection of Jesus as occurring on the Sunday morning directly after Passover, why is it that in many years both Eastern and Western Christians celebrate Easter more than a week after Passover, or even before Passover? The major key to understanding the cycle of annual dates for Passover, Orthodox Easter, and Western Easter is the Metonic Cycle, and how it was shaped and applied in three different historical contexts. This article seeks to explore the historical genesis of the Metonic Cycle and how it was applied to each of...