Visual mental imagery protocols can provide step-by-step traces of executive decisionmaking. Sequences of drawings that externalize thought processes are often easier to analyze than transcriptions of tape recorded verbal protocols. The technique is of obvious use for investigating spatial problem solving behavior since such tasks are usually solved with sketches, drawings, or graphs; the methodology is also appropriate for abstract, non-spatial decisionmaking for which mental images often function as models that managers mentally construct and manipulate. This paper reports an application to the analysis of decisions by a high level executive: the commander of a naval task force. The study will influence both design and evaluation of the command and control systems that support tactical decision making by such commanders and their staffs, over long periods, in hostile environments under extreme stress.