In this volume of 382 pages, Commissioner Lewis speaks from careful observation and from conscientious study. The reader will soon perceive that a judicial treatment is applied to the various questions involved in dealing with penological problems. Various systems of government are considered, the differences between the Honor System and the Self-Government clearly indicated, and valuable suggestions made as to the classes of prisoners to which the various systems of government may be adapted. The subjects of Probation and The Indeterminate Sentence are fairly presented and discussed, the author coming to the conclusion that the Indeterminate Sentence is far preferable to the determinate system of the older penology. The tendency today is to treat the offender in much the same way as the insane are now treated. Originally these unfortunates were dealt with as though possessed of demons. Gradually a reform was introduced. Special institutions were established, and these have been gradually improved to the extent that such afflicted persons are given such occupation and such freedom as compatible with safety. The result is that from 20 to 30 per cent. of them are either released as cured or may be released under the custodial care of their friends or relatives. Mr. Lewis holds that the tendency to accord similar treatment after a careful diagnosis of each case to the delinquent is likely to produce a similar result. Each offender should be dealt with according to his special peculiarity, the treatment aiming at the substitution of good for bad habits, commitment to prison being used when it is not in the interest of the individual or of society to release the convicted criminal. Mr. Lewis advocates the retaining of old-established methods as long as they are of service. These should not be discarded merely because they are old. He claims that the leaders in the movement agree that the new methods should be wisely tested before they are introduced generally. It is clear that there must have been good reasons for the adoption of any new method, but at the same time he is strongly in favor of studying the human equation, and of differentiating the treatment to suit each case. In order to administer intelligently the large department under his charge he has “found it necessary to proceed carefully and to experiment widely before effecting a departure from the well-known methods of treatment.” The processes as well as the result of Mr. Lewis’s labors are given in the present volume. In Part I he rehearses the fundamental social forces upon which one must depend in order to check the development of the criminal. Among these are the home, the church, the school, health and sanitation, and the police.