While the DARPA Structural Integrity Prognosis System (SIPS) and the Engine System Prognosis (ESP) programs focus on very different application domains, both programs have a common Reasoning and Prognosis element with the same objective; to provide the best possible decision support to maintainers and operators.  Though SIPS addresses aging aircraft structures and ESP life limiting gas turbine engine components, there is the common challenge of fusing sparse and imperfect data with physics-of-failure models to arrive at the most accurate estimates of remaining useful life possible.  Such capability is truly game changing in that it allows critical assets to be managed on the basis of actual failure risk rather than in costly scheduled intervals.  This presentation will summarize the Reasoning and Prognosis methodologies “under the hood” for both programs and provide demonstrations of the software applications that now embody them.