The police have many functions and responsibilities. Indeed, understanding the balance between these has led to considerable academic debate. For many commentators the core function of the police is the maintenance of order. Others point to the role of police forces as ‘secret social services’. In the public mind, however, in addition to the provision of reassurance, it is undoubtedly the case that it is the prevention, investigation and detection of crime that is seen as the central part of the police mandate. Interestingly, crime investigation has not generally been a subject of significant academic scrutiny. That is beginning to change, however, and in this volume we examine the history, theory, policy and practice of investigation. As with all areas of policing, however, it is important to understand these activities in their broader institutional and social context.