The ornate box turtle, _Terrapene o. ornata_ Agassiz, was studied more or less continuously from September, 1953, until July, 1957. Intensive field studies were made of free-living, marked populations in two small areas of Douglas County, Kansas, in the period 1954 to 1956. Laboratory studies were made, whenever possible, of phenomena difficult to observe in the field, or to clarify or substantiate field observations. Certain phases of the work (for example, studies of populations and movements) were based almost entirely on field observation whereas other phases (for example, growth and gametogenic cycles) were carried out almost entirely within the laboratory on specimens obtained from eastern Kansas and other localities. A taxonomic revision of the genus _Terrapene_ was begun in 1956 as an outgrowth of the present study. The systematic status of _T. ornata_ and other species is here discussed only briefly. Objectives of the study here reported on were: 1) to learn as much as possible concerning the habits, adaptations, and life history of _T. o. ornata_; 2) to compare the information thus acquired with corresponding information on other emyid and testudinid chelonians, and especially with that on other species and subspecies of _Terrapene_; 3) to determine what factors limit the geographic distribution of ornate box turtles; and, 4) to determine the role of ornate box turtles in an ecological community. Acknowledgments The aid given by a number of persons has contributed substantially to the present study. I am grateful to my wife, Avis J. Legler, who, more than any single person, has unselfishly contributed her time to this project; in addition to making all the histological preparations and typing the entire manuscript, she has assisted and encouraged me in every phase of the study. Dr. Henry S. Fitch has been most helpful in offering counsel and encouragement. Thanks are due Professor E. Raymond Hall for critically reading the manuscript. Special thanks are due also to the following persons: Professor A. B. Leonard for helpful suggestions dealing with photography and for advice on several parts of the manuscript; Professor William C. Young for the use of facilities at the Endocrine Laboratory, University of Kansas; Professor Edward H. Taylor for permission to study specimens in his care; Dr. Richard B. Loomis for identifying chigger mites and offering helpful suggestions on the discussion of ectoparasites; Mr. Irwin Ungar for identification of plants; and, Mr. William R. Brecheisen for allowing me to examine his field notes and for assistance with field work. Identifications of animal remains in stomachs were made by Professor A. B. Leonard (mollusks, crustaceans), Dr. George W. Byers (arthropods), and Dr. Sydney Anderson (mammals).