This is the third edition of a distinctive text which has been one of the leaders in its field since it was first published in 1946. The first edition was noteworthy for the breadth of viewpoint of its experienced author (Smillie); for its graceful dedication to Lemuel Shattuck, the remarkably public-healthminded Bostonion book seller of a century ago whose apt statements were liberally quoted; for its thorough coverage of the field; and for the usefulness of its frequently quoted definitions of "preventive medicine" and "public health." The second edition, in 1952, changed the format little in bringing the book up-to-date, but the present edition has been more extensively revised in format, as well as in content, while retaining much of the flavor of the original. Kilbourne has revised extensively the coverage of infectious diseases which are classified in a particularly useful epidemiologic fashion. Bross has revised the material on biostatistics.