Of the three main festivals in the Hebrew Bible, only the Festival of Weeks, or Pentecost, is not explicitly associated with an historical event. However, by the rabbinic period, the rabbis commonly associate the Festival of Weeks with the giving of the Law at Mt. Sinai. This study attempts to trace the development of the association between the events at Sinai and the Festival of Weeks. The Festival of Weeks was originally a harvest festival that eventually acquired a religious significance. In the Hebrew Bible, the precise date of the Festival of Weeks is indeterminable, but it did occur sometime during the third month. There are already indications that the Festival of Weeks was associated with covenant renewal (2 Chr 15:10), but this association is at best muted. It is only with the book of Jubilees that there is an explicit connection between the Festival of Weeks and covenant renewal. In this book, the Festival of Weeks is dated to the fifteenth day of the third month. The most notable feature of Jubilees' covenant theology is that the Abrahamic and Mosaic covenants are depicted as renewals of the original covenant with Noah. With the publication of virtually the entire Qumran corpus, it is now clear that the Qumran covenanters, for whom the book of Jubilees was highly revered, also celebrated the Festival of Weeks as the day of covenant renewal on the fifteenth day of the third month. Finally, the account of Pentecost in Acts 2 shows numerous allusions to Moses and the Israelites at the foot of Mt. Sinai. Moreover, this fits in with Luke's portrait of Jesus as the prophet like Moses and the Isaianic New Exodus theme that permeates the two volume work. By means of these allusions, Luke depicts Jesus' giving of the Spirit to his followers as the inauguration of a new community, marked not by the Law, but by the Spirit.