Abstract. Most current software systems cannot adapt to changing hardware requirements or changing operational environments. This lack of adaptivity shortens the life of the software and makes it less capable of achieving its mission. We are developing Probabilistic Representation of Intent Commitments to Ensure Software Survival (PRINCESS) to enable software to adapt to both hardware changes and changing environments. We are developing methods to automatically optimize software for new environments, turning non-adaptive code into optimizable adaptive code. We are also developing sensor adapters that enable us to maintain software function despite changing or failing sensors. We are implementing PRINCESS on the navigation system of an unmanned undersea vehicle. An independent evaluation has demonstrated PRINCESS's ability to adapt to degraded sensors, changing environmental conditions, and loss of power.