Abstract: Through most of our period, the intercalation of a thirteenth month to the year (designed to bring the lunar calendar in line with the annual seasons) was independently carried out by the Jewish communities in Palestine and the diaspora, so that their calendars and festival dates were often at variance. Until the first century c.e., Jewish lunar calendars tended to be late in relation to the solar year: thus, Passover would usually occur after the spring equinox. By the fourth century, however, Passover was frequently celebrated before the equinox, as is amply documented in Christian sources relating to the date of Easter. Diversity of practice between various Jewish communities persisted until the end of Antiquity (e.g. at Zoar).

Keywords: diversity, Easter, equinox, festival dates, intercalation, Passover, Zoar,