Both stable personality characteristics (traits) and transient emotions (states) influence cognition and behavior. In this paper, we describe a methodology for modeling these effects in terms of a set of parameters that control processing within a symbolic cognitive architecture. The underlying thesis of the approach is that the combined effects of these individual differences can be modeled by varying the architecture parameters that control both processing and the structure of knowledge within the architecture modules. We describe the architecture, provide operational definitions of representative trait and state influences in terms of the controlling parameters, and demonstrate how observed trait/state phenomena are modeled in the context of the current demonstration scenario: a peacekeeping training simulation.