Success in counterinsurgency (COIN) operations relies on the application of new knowledge and the creation of mental models for dealing with novel problems. Current training programs for improving cognitive readiness are inadequate because they do not always replicate conditions, and feedback to the Warfighters is not decision-centered. A fresh approach to framing the training needs and for designing training solutions is needed to improve the ability of Warfighters to quickly decide and act in complex adaptive environments. This paper describes the development of a scenario design tool that helps to bridge the gap between training developers and training requirements, by facilitating the preparation of decisioncentered training scenarios by training developers, small unit leaders, and simulation center staffs. Cognitive task analysis (CTA) methods were applied to reveal the mental models of experienced Warfighters who had demonstrated critical cognitive competencies in a COIN setting. From these data, a set of decisions and judgments typical of operations in COIN environments was identified. For each decision or dilemma, we identified the set of critical cues and factors that were used to recognize a pattern, detect an anomaly, or forecast next events. These elements were validated and used to specify a decisioncentered training design. A scenario design tool was constructed around these decisions and judgments to support the development of decision-centered training scenarios in both current and future COIN mission contexts. The scenario design tool can be adapted to several training platforms, since it focuses on the cognitive fidelity of the training content and not the training technology. This tool will assist training designers in identifying the necessary conditions that will reinforce learning once they have identified the training requirements.