This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book presents two inter-related themes: the process of criminalisation and responses to crime and criminal activity. It explores the processes by which certain activities are labelled as criminal and thereby come within the remit of a range of criminal justice agencies. The contributions span the historical perspective. The book describes the researching responses to crime and criminal activity. In addition, it explores a historical perspective and evaluates qualitative methods pertinent to a retrospective analysis. Although the contributors to the book all demonstrate a commitment to the value of qualitative approaches, the book also contains a critical reflection of the use of different qualitative techniques and discusses potential problems and difficulties.