We noted in the Preface that we are indebted to the hundreds and perhaps even thousands of authors who have worked in the area of drug misuse and crime. However, our contribution to this debate has also been influenced by people closer to us who have affected our thinking in various ways. These include the various staff at the Home Office with whom we have worked in the area of drugs and crime for nearly a decade. We are also grateful, of course, to the Home Office for funding research that has helped us to review and conduct research in this area. We are particularly indebted to the various researchers who have worked with us over the years. They are too numerous to mention by name (the NEW-ADAM programme employed over 30 researchers at various times). However, we would like to note our thanks to the research staff who worked with us most recently on the systematic reviews of the literature, including Catherine Appleton, Stephen Brown and Tracy Pitman. We are also grateful to the series editor, Mike Maguire, for his very helpful comments on earlier drafts of the book. It goes almost without saying that he is in no way responsible for our errors. We would also like to thank the many other people who have given us ideas, influenced our thinking, or suggested references.