[en] The DIII-D device is a large tokamak used for experimental research into the physics and technologies needed for the application of fusion energy to the needs of society. DIII-D is located in San Diego, California on a site provided by General Atomics (GA). The device was originally constructed under DOE (then ERDA) contract as Doublet III and commissioned in early 1978. The device has since been operated, upgraded, and through this project, modified (to DIII-D) under contract to DOE. The DIII-D Vessel Modification Project was partially funded by the Japan Atomic Energy Research Institute (JAERI) as part of a nine-year cooperative research program on Doublet III. In addition, JAERI funds provided for earlier major upgrades to the DIII facility, particularly in the power and neutral beam heating systems. These upgrades have been fully incorporated into the DIII-D facility. This report summarizes the scope, cost, and schedule of the Vessel Modification Project, and indicates any major changes that were made as the project progressed. Numerous separate scientific and engineering papers describe more fully the details of the design and expected performance of the device and are referenced in the Appendices