This volume is the outgrowth of an extension course conducted by Reed College in Portland, Oregon, in 1913. The course was offered to teachers and to workers in various other fields of social service as an outline of the main problems of social hygiene and morals and as a guide to further study. An edition of forty-five hundred copies of the syllabus of the course was soon exhausted, and there appeared to be a sufficient demand for the publication of some of the lectures.