The second chapter of Acts places the apostles together in Jerusalem on the day of Shavuot, the Jewish pilgrim festival that drew Jewish visitors from across the Mediterranean and Near Eastern world to the city, which is why the crowd that gathered is described as hearing the apostles' speech each in their own language. The text describes a sound like a rushing wind filling the house, something like tongues of fire resting on each person present, and the apostles beginning to speak in other languages. Peter's address to the crowd that follows interprets the event through the prophet Joel's promise that God would pour out his spirit on all people, and Acts reports that about three thousand people were added to the community that day, a figure the text itself supplies with no independent outside corroboration.
The Greek name Pentecost, meaning fiftieth, reflects the festival's place fifty days after Passover in the Jewish calendar, and because Easter's date moves with Passover, Pentecost moves with it in the Christian calendar as well. Acts lists the regions the visiting pilgrims are said to have come from, a roll call spanning Mesopotamia, Asia Minor, Egypt, Rome and Arabia, which the narrative uses to signal that the message that day reached the whole known Jewish diaspora rather than a purely local audience, an image later Christian interpretation extended into a claim about the church's reach among all nations.