This text is intended to provide a strong theoretical background in testing hypotheses and decision theory for those who will be practicing in the real world or who will be participating in the training of real-world statisticians and biostatisticians. In previous editions of this text, my rhetoric was somewhat tentative. I was saying, in effect. "Gee guys, permutation methods provide a practical real-world alternative to asymptotic parametric approximations. YVhv not give them a try?" But todav. the theorv. the software, and the liardware have come together. Distribution-free permutation procedures are the primary method for testing hypotheses. Parametric procedures and the bootstrap are to be reserved for the few situations in which they may be applicable.