This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book offer a new orienting perspective, a different way of perceiving reality, under which existing theories may be used and reinterpreted. It provides an overview of criminological theorizing from the 1970s to the present. The book presents an overview of the theoretical field, particularly the work of the past two decades, and review the similarities and differences between the various perspectives. It examines reasons for the failure of theory to adequately deal with the reality of crime. The book examines the use of concepts and the way people formulate and measure them. It deals with a discussion of the way in which definitions of crime have hampered work, continues with an examination of how critical explanatory variables have been conceived and measured, and concludes with some suggestions for improving measurement.