Book excerpt: This book brings together leading international criminologist to examine the link between the fruits of criminological research and the development of criminal justice policy. This volume includes comparative discussions of the United States, Germany, Australia, England and Wales. It is divided into four parts: Part 1 discusses the theoretical issues surrounding the relationship between public policy and the discipline of criminology; Part 2 consists of three essays exploring historical aspects of that relationship. Part 3 then examines three distinct areas of penal policy: sentencing, policing and parole; Part 4 is devoted to international comparisons and considers the factors that distinguish research projects that influence criminal justice policy from those that appear not have any influence.