Howard E. Barbaree, PhD, is Professor and Head, Law and Mental Health Program, Department of Psychiatry, University of Toronto, and Clinical Director, Law and Mental Health Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada. He has devoted much of his career to research, teaching, and clinical practice related to sexual aggression and sexual deviance. Dr. Barbaree has published numerous journal articles and book chapters and is coeditor of the Handbook of Sexual Assault: Issues, Theories, and Treatment of the Offender (1990). He has served as a member of the National Institute of Mental Health Violence and Traumatic Stress Grant Review Committee and received the Significant Achievement Award from the Association for the Treatment of Sexual Abusers in 2000. In 2004 Dr. Barbaree began a 4-year term as editor of Sexual Abuse: A Journal of Research and Treatment. William L. Marshall, PhD, is Professor Emeritus of Psychology and Psychiatry at Queen's University and Director of Rockwood Psychological Services, Kingston, Ontario, Canada, which provides sex offender treatment in two Canadian federal penitentiaries. Dr. Marshall has 35 years of experience in assessment, treatment, and research with sexual offenders and has over 300 publications, including 16 books. He was President of the Association for the Treatment of Sexual Abusers from 2000 to 2001 and received its Significant Achievement Award in 1993. In 1999 Dr. Marshall received the Santiago Grisolia Prize from the Queen Sophia Centre in Spain for his worldwide contributions to the reduction of violence, and in 2000 he was elected a Fellow of the Royal Society of Canada. In 2003 Dr. Marshall was one of six invited experts who were asked to advise the Vatican on how best to deal with sexual abuse within the Catholic Church.