Rickettsiae comprise a group of paleomorphic, coccobacillary microorganisms that are now regarded as true bacteria. Nicholas Rahon presents a collection of papers that deal exclusively with pathogenic rickettsiae. The selected papers—twenty-nine in all and fully illustrated—range from the sixteenth century to the modern era. A number of the papers are classics in the field and several of the selections appear in English translation for the first time. The editor provides a preface to each selection and his general introduction defines the subject matter, surveys historical developments in the field, and summarizes recent research.