Postpenal measures are neither penalties nor therapeutic security measures; they are either a continuation of resocialization efforts begun during incarceration or a complement to the penalty after release. Socialist doctrine rejects the traditional concept of security measures because of their antihumanitarian bias. In the socialist view, human behavior can be corrected at any point in development. Thus, postrelease measures are based on the conviction that individuals can be reeducated. After recidivists have served their time, socialist educators focus on modifying their personalities, convictions, habits, and attitudes and on changing their environments. Postpenal constraint measures are practiced as administrative supervision of released prisoners in the USSR, state educational and supervisory programs in East Germany, protective supervision in Czechoslavakia, and protective supervision and readaptation in Poland. In some socialist countries only recidivists, in others all prison releasees, are placed under postrelease supervision. The supervisory systems in all the countries mentioned are less than 10 years old. Mechanisms for placing ex-convicts under supervision, its terms and duration, and the types of restrictions imposed vary from country to country. Another form of postrelease measure is the postcure, which provides assistance to releasees in finding jobs, lodgings, and other necessities. Protective supervision is facilitated by social readaptation centers, where courts place ex-convicts in order to test and increase their degree of adaptation and to protect society against new offenses by multirecidivists. Postrelease measures, especially postcure programs, involve a large part of society in their efforts to strengthen ex-convicts' ties with their places of employment and their families. Postpenal measures can be classified by agencies authorized to apply them as judicial, administrative, or mixed, depending on the laws of the country in question. Studies of these systems are needed to determine whether their measures prevent recidivism, contribute to resocialization, and protect society against crime. Notes and a 38-item bibliography are supplied.