This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book challenges the reader to balance the available evidence/arguments and to formulate their own critical views on how best to understand and respond to youth offending in the modern world. It presents an historical overview of the development of explanatory theories of offending. The book explores the chronological and simultaneous explanatory evolution of a group of theories that understand youth offending as the result of exposure to 'risk factors', which predicts an increased likelihood of offending in the future. It provides a detailed exploration of the significant youth justice developments in England and Wales under the New Labour Government that seized power in 1997. The book brings youth justice up-to-date by evaluating contemporary developments in youth justice in England and Wales since the fall of New Labour in 2010.