Two thousand years ago, a Jewish fisherman stood up before a crowd of thousands to explain an extraordinary event. A bewildered crowd had heard the wonders of God being declared in their own languages. Peter's explanation? This was the fulfillment of the promise of the prophet Joel--a promise that in the last days people would prophesy, see dreams and visions, and perform signs and wonders. That extraordinary day and that extraordinary promise have shaped the church over the last two thousand years. The question before us is, what does it mean for us today? This book seeks to address and answer some of those questions by examining carefully the verses in question, Acts 2:17-21, and their wider context and purpose.