An Ultralight Weight Door (ULWD) has been developed that is 40% lighter than a baseline 2016 mid-size vehicle’s driver side door. The ULWD scope encompasses the entire door, including the door-in-white (DIW), interior trim, glazing, hardware, wiring, etc. To achieve such a substantial mass reduction while still meeting the baseline vehicle’s performance metrics (including safety, durability, NVH, appearance, etc.) at a minimal cost increase, the door design relies on a comprehensive full system approach that includes a unique architecture in addition to lightweight materials and components. To optimize the strength and weight of the ULWD, a new aluminum intensive DIW architecture construction was developed. The new structure features 5000 series and 6000 series aluminum stamped panels, aluminum vacuum die cast, and warm formed 7000 series aluminum door beam. The ULWD utilizes an electronic latching system and a unique door module/window subsystem architecture enabling the integration and elimination of parts. The other door sub-systems were then designed to be integrated within the ULWD architecture and optimized for mass. This paper details the ULWD design concept, simulated performance results, the current status of vehicle level validation, and comparisons between component level CAE predicted performance and physical test results.