There is a need to develop descriptive models of decision making under conditions of risk, ambiguity, and time pressure. As part of an ongoing effort to develop such a model, the present study performed a Critical Decision analysis of decisions made by 12 Expert and 12 Novice fire ground commanders. A coding system was developed for this study and 104 decision points were classified and described. The findings do not support the prevalent view of decision making as evaluation between options. 54% of the decision points relied most extensively on predecisional processes involving problem identification and clarification, 15% involved questions of specific timing or control, and 13% involved serial evaluation of a single option. Thus, only 18% of the decisions involved concurrent option evaluation. Differences between Expert and Novice commanders are also discussed.