Although individuals often work in groups and groups function within a larger environment, researchers have rarely examined the effect of context on employees’ emotions, attitudes, or behaviors. This study uses the World Trade Center attack to generate and test a context theory concerning the impact on first responders of their involvement in a catastrophic event. The model details the way in which the climate (support from supervisors and employee control over the work environment) within discrete engine and ladder companies (work units) moderates the relationship between emergency response to the attack (the stressor) and the resulting emotional strain on the firefighters. Prior studies have shown that people’s exposure to critical incidents is associated with depression, anxiety, and stress that may begin immediately or surface months later. The severity of individual reactions varies and researchers have proposed several explanatory theories, including biological and psychological factors, the way people mentally process their experiences, and the array of physical and social/emotional resources at their disposal. The authors here draw on the latter two theoretical frameworks to formulate and test several hypotheses that help explain why New York City firefighters involved in 9/11 felt more or less emotionally wrought 18 months after the attack.