Structural dynamic programming models are a powerful tool to help guide policy under uncertainty. By creating a mathematical representation of the intertemporal optimization problem of interest, these models can answer questions that static models cannot address. Applications can be found from military personnel policy (how does future compensation affect retention now?) to inventory management (how many aircraft are needed to meet readiness objectives?). Recent advances in statistical methods and computational algorithms allow us to develop dynamic programming models of complex real-world problems that were previously too difficult to solve.