"Hajek was undoubtedly a statistician of enormous power who, in his relatively short life, contributed fundamental results over a wide range of topics..." V. Barnett, University of Nottingham. Hajeka s writings in statistics are not only seminal but form a powerful unified body of theory. This is particularly the case with his studies of non--parametric statistics. His book "The Theory of Rank Test", with ?idak, was described by W. Hoeffding as almost the last word on the subject. Hajeka s work still has great importance today, for example his research has proved highly relevant to recent investigations on bootstrap diagnostics. Much of Hajeka s work is scattered through the literature and some of it quite inaccessible, existing only in the original Czech version. This book provides a valuable unified text of the collective works of Hajek with additional essays by internationally renowned contributors. Undoubtedly this book will be essential reading to modern researchers in nonparametric statistics.