FULL PROPOSAL: The Systems Science (SYS) program supports fundamental research leading to a theoretical foundation for design and systems engineering. In particular, the Systems Science program seeks intellectual advances in which underlying theories (such as probability theory, decision theory, game theory, organizational sociology, behavioral economics or cognitive psychology) are integrated and abstracted to develop explanatory models for design and systems engineering in a general, domain-independent fashion. Ideally, the explanatory models, derived from the underlying theoretical foundations will lead to testable hypotheses. Based on collected evidence supporting or falsifying the hypotheses, new insights are gained allowing the explanatory models to be refined or updated. Systems research that does not address the Engineering of Systems is out of scope. Domain-specific applications of the theoretical foundations are also out of scope. Research that focuses on domain-specific applications, but simultaneously advances our fundamental understanding of design and systems engineering will be considered for co-funding with other programs.