"This is the most comprehensive and thoughtful work ever done on undercover policing. It will be the benchmark by which all further scholarship in this area will be judged."—Jerome Skolnick, University of California, Berkeley, School of Law "If you believe in undercover tactics, this book will warn you. If you are opposed to covert activities by the police, this excellent study will force you to rethink your position. . . . Undercover is indispensable for anyone who wants to understand the threat, but also the usefulness, of surveillance by law enforcement officials."—R. Drinan, Georgetown University "Gary Marx's book is one of the best of the rare species, thoughtful and analytic books about police surveillance. He has a thousand stories, most of them current . . . and he makes a solid study out of them. He has written a sociological map for surveillance, giving it a structure that it has never before had."—P. Chevigny, New York University "This is the best single treatment of the problem of undercover investigations in our literature. Gary Marx writes not only with erudition and sensitivity, he is a very sensible man as well. He has mastered a vast amount of detail while not losing sight of the big picture. I cannot praise this book too highly."—J. Kaplan, Stanford University "A tour de force on a very difficult subject. . . . This is an important, needed, well-executed book. It will be widely read and used."—D. Bayley, State University of New York, Albany "A remarkable success at weaving legal and sociological factors in an otherwise controversial and seemingly irreconcilable interplay of disciplines."—J. Wilczynski, Prosecutor's Brief "A wonderful book!"—Professor Arthur Miller, C-NBC Live "Deserves a wide audience beyond practitioners and scholars."—A. Bouza, Chief of Police, Minneapolis