In the twentieth century Pentecost has become a source of confusion, embarrassment or division for Christians, even as it has become a curiosity, if not an object of ridicule, for non-Christians. What is repeatable—and what is unrepeatable—of that miraculous outpouring of the Spirit and speaking in tongues? Luke helps us sort through our various reactions so Pentecost can become the comfort and the challenge it was meant to be. Peter's speech speaks to the cause and significance of the event.