The session consists of four papers: Real Time Diagnostics of Problem-Solving Behavior for System Dynamics-Based Business Simulations; Sensitivity Analysis of an Infectious Disease Model; Leveraging a High Fidelity Switched Network Model to Inform a System Dynamics Model of the Telecommunications Infrastructure; and Critical Infrastructure Protection Decision Support System. The first paper concerned supporting learning in and about complex problems. The paper describes the diagnostics of the problem solving process, i.e. of the information-retrieval and decision-making processes, as prerequisite for effective “feedback” to the learner. The second paper describes a model of infectious diseases that has been developed for integration within a larger simulation structure to assess the interdependencies of critical infrastructures. This paper presents the preliminary sensitivity analyses of the effects of inputs to the infectious disease model on the calculated consequences. The third paper summarizes the results of a collaborative effort with Bell Laboratories, Lucent Technologies to leverage a detailed switched network simulation to inform the telecommunications system dynamics model in a Critical Infrastructure Protection Decision Support System (CIP/DSS). The fourth paper describes CIP/DSS and simulates the dynamics of individual infrastructures and couples separate infrastructures to each other according to their interdependencies.