This new book, cleverly entitledEeyondthe Kalman Filler, is by far the best book on filtering published in many years: It is clearly written, well organized, authoritative, and contains a wealth of useful information. It explains a state-of-the-art class of practical nonlinear filtering algorithms, called ''pam.de filrers," using examples and theory accessible to normal engineers. The book contains many examples of practical nonlinear filters worked out in detail. One of the best features of the book is the large variety of plots of filter estimation accuracy for different types of filters, including the extended Kalman filter (EKF), the unscented Kalman filter (UKF),