This is a revised edition of a work originally published in 1929. In it, certain statistics have been substituted for old ones; some new material has been added, and old material rearranged. Those portions dealing with the problem of the cost of medical care and its causes have been rewritten. A discussion of the recent experience of Chicago in tracing an epidemic of amebic dysentery to defective plumbing is included. The book, in general, presents facts concerning the promotion and safeguarding of public health that are felt to be essential to the mental equipment of every college man and woman. It should make a useful textbook for the teaching of community hygiene.