The purpose of this new classification compendium is to republish the Orthopaedic Trauma Association's (OTA) classification. The OTA classification was originally published in a compendium of the Journal of Orthopaedic Trauma in 1996. It adopted The Comprehensive Classification of the Long Bones developed by Müller and colleagues and classified the remaining bones. In this compendium, the introductory chapter reviews new scientific information about classifying fractures that has been published in the last 11 years. The classification is presented in a revised format that is easier to follow. The OTA and AO classification will now have a unified alpha-numeric code eliminating the differences that have existed between the 2 codes. The code was significantly revised for the clavicle and scapula, foot and hand, and patella. Dislocations have been expanded on an anatomic basis and for most joints will be coded separately. This publication should stimulate new developments and interest in a unified language to code and classify fractures. Further improvements in classification will result in better patient care and clinical research.