This chapter describes the use of extinction and punishment procedures in applied settings. Punishment and extinction describe processes which result in a reduction or elimination of behavior. With extinction the contingency between the reinforcer and response is removed. Punishment involves the application or removal of a stimulus contingent on the performance of the target behavior. Prior to using extinction and punishment it is important that the behavior analyst establish a firm rationale for reducing targeted behaviors. The use of some of these strategies, particularly the use of aversive stimuli as punishers, should be considered the treatment of last resort and administered under strict guidelines. Typically, extinction and punishment protocols are used to eliminate aberrant behavior in the context of an intervention to increase appropriate alternative behaviors for the person. One of the major advantages of punishment techniques is that they can produce rapid elimination of the maladaptive behavior.