The effects of a number of situational variables on decisions to be flexible or inflexible were explored in a simulation of an international negotiation on the regulation of gases contributing to the depletion of the ozone layer. Four negotiating-stage scenarios were created, each consisting of a particular combination of variables arranged into three experimental conditions. The experiment was run with two international samples, one consisting of scientists, the other of diplomats from different countries. The hypothesized differences among the conditions were obtained for both samples. Using a pair-comparisons format, participants were asked to judge the relative importance of the variables, within stages, in producing flexibility. Analyses of these judgments revealed trajectories of factors leading to agreement or to stalemate for both samples. These results were also compared with those obtained from a meta-analysis of earlier experiments examining similar variables. The simulation results, based on combined impacts of variables, were stronger than those obtained in the earlier experiments where variables were manipulated one at a time.