This volume, as its title indicates, is occupied with an examination of some of the principal causes of crime, and is designed as an introduction to the study of criminal questions in general. In spite of all the attention these questions have hitherto received and are now receiving, crime still remains one of the most perplexing and obstinate of social problems. It is much more formidable than pauperism, and almost as costly. A social system which has to try hundreds of thousands of offenders annually before the criminal courts is in a very imperfect condition; the causes which lead to this state of things deserve careful consideration from all who take an interest in social welfare.