This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book aims to apply state-of-the-art sociological theorizing and several anthropological analytical frameworks to Alpha, and to consider their relevance by way of the empirical data uncovered. The principal concern is in understanding the Alpha ‘product’ in terms of the dynamics of a ‘spiritual marketplace’. The book considers the various categories of people who join up and their experiences of Alpha, including those who have been converted, those who left early, and those who saw out the programme but have decided that Christianity was not for them. It provides a more rigorous and focused academic approach, and perhaps more considered reflection in coming to grips with the subject of Alpha through a much larger survey conducted on a national scale. Its perspective is largely sociological and is not without its difficulties.