Alex R. Piquero is a Professor at the University of Maryland Department of Criminal Justice and Criminology, Member of the MacArthur Foundation's Research Network on Adolescent Development, and Member of the National Consortium on Violence Research. He is also Executive Counselor of the American Society of Criminology, and is Co-Editor of the Journal of Quantitative Criminology. He received a Ph.D. in Criminology & Criminal Justice from the University of Maryland in 1996, and has received several teaching, research, and mentoring awards, including the American Society of Criminology Young Scholar and E-Mail Mentor of the Year Awards, and a University of Florida Teacher of the Year Award. His research interests include criminal careers, criminological theory, and quantitative research methods. He has published widely in the fields of criminology, criminal justice, psychology, and sociology, and is co-author (with Alfred Blumstein and David Farrington) of a recently published book, Key Issues in Criminal Careers Research. David Weisburd is Walter E. Meyer Professor of Law and Criminal Justice and Director of the Institute of Criminology at the Hebrew University Faculty of Law, and Distinguished Professor of Administration of Justice at George Mason University. He is an elected Fellow of the American Society of Criminology and of the Academy of Experimental Criminology. He is also Co-Chair of the steering committee of the Campbell Collaboration Crime and Justice Group, a member of the Harvard University/National Institute of Justice Executive Session in Policing, and of the National Research Council Committee on Crime, Law and Justice. Professor Weisburd has a long interest in Crime and Place studies beginning with his involvement in a series of experimental studies of police interventions at crime places, including the Minneapolis Hot Spots Experiment, the Jersey City Drug Market Analysis Experiment and the Jersey City Violent Crime Hot Spots Experiment. Professor Weisburd is presently working on a book with Liz Groff and SueMing Yang that explores the varying factors that explain variation in developmental trends of crime at micro places over time that will be published by Oxford University Press. Professor Weisburd is author or editor of fifteen books and more than eighty scientific articles.