We would like to thank the University of Southern California, the National Institute on Drug Abuse and the National Cancer Institute for giving us the flexibility to write this text. We also would like to thank Open University Press and Stephen Sutton for their interest in working with us. We have tried to provide an international relevance to the book. We also would like to thank our previous Health Promotion 410 students who helped us to clarify concepts during classroom instruction of drug abuse issues. Also, we would like to thank Beth Howard and Jennifer Zoff for their editorial assistance and Alan Stacy for providing a flexible and supportive research environment. Finally, we would like to thank our families (Rotchana, Guang, Evan, Max, Woody, Mikey, Terry, Bill, Karen and Pam) for providing the balance in our lives that makes a text like this one a treat.