The physical difficulty of designing entry vehicles originates from the large degree of coupling between the various disciplines involved in the design. Every subsystem design decision has far reaching consequences that must be evaluated in a multidisciplinary fashion in order to assess the impact on the weight and the performance of the entire vehicle. The disciplines which must be accounted and integrated during the design are: trajectory optimization, guidance, navigation, and control (GN&C) technology, aerodynamics and aerothermodynamics, thermal-structural analysis, and thermal protection system (TPS) development. Previous efforts in developing a collaborative or a multidisciplinary optimization process never considered how uncertainty in the atmospheric conditions, in the entry parameters of the vehicle, in the condition of the vehicle during entry, and in the performance of the TPS will influence the design and provide a risk assessment for a mission. The work completed during the Phase I effort demonstrated that it is feasible to develop a tool for multidisciplinary optimization under uncertainty (MDO-U) for entry vehicle design, and the new information which is gained is insightful and meaningful. The functionality and the value of the new MDO-U design tool were demonstrated through a case study where MDO-U was performed for the HL-20 vehicle under a LEO consideration. During Phase II a general purpose and user friendly MDO-U product which can be used in entry vehicle design, and in many other engineering areas will be developed.