The wars in Iraq and Afghanistan highlighted the need for small unit leaders to have the skills necessary to effectively operate in increasingly distributed and autonomous operations. Critical to this is development of skills to make effective decisions under the stress of the battlefield. To address this need, the Marine Corps is implementing the Infantry Small Unit Leaders Course (ISULC) to train Infantry Sergeants to "identify problems, develop problems/situations, formulate and communicate decisions, [and] adapt to changing conditions (Fitzpatrick, 2011, p.1). In this paper we describe a simulation-based training approach to aid in the development of small unit leader decision-making skills that are resilient to stress. This approach is based on the previously presented theoretical framework (Carroll et al., 2012) and incorporates validated stress induction and training techniques into a simulation-based training curriculum. The approach is being developed to effectively train small unit leaders within the time, staffing, and technology constraints of schoolhouse environments and integrates three components to achieve this goal. The basis of the approach is an event-based methodology in which simulation scenarios incorporate a series of related decision events based on target training objectives. Next, innovative assessment techniques are used to capture behavioral measures of decision-making at the process level (i.e., Observe, Orient, Decide, Act (OODA)) and physiological measures of stress response to facilitate an understanding of breakdowns in decision-making under stress. Finally, the approach incorporates learning strategies (e.g., pre-training, feedback) designed to target the decision-making process as well as stress appraisal and coping skills. This paper will describe the simulation-based training approach, including scenario design techniques, decision-making and stress measures, and learning strategies. Conclusions and future work will then be discussed.