This study examines situation versus personality effects on foreign policy decision making. It proposes that while both factors are important in explaining decision outcomes, the relative importance of each in a given circumstance is a function of the structural constraints imposed by the policy decision environment. Following Maoz (1990) and Maoz and Astorino (1992b), a decision-game theoretic framework is used to "reconstruct" policy decision problems in order to study individual and environment effects concurrently. The substantive focus is the ten decisions that comprised the major events of the 1970 Civil War in Jordan. The decision reconstructions are used to rate these decision tasks according to the presence and degree of structural constraint. Although it represents a preliminary test, the decision analysis indicates that in structurally constrained decision settings, policymakers tended to respond in accordance with environmental clues, while response variability and evidence of simplifying decision heuristics was greater in more fluid decision settings.