Positive and negative affect influence an individual's ability to utilize available physical, psychological, and social resources to maximize responses to life events. Little research has examined the factors that influence the development of positive affect or reduction of negative affective responses among deployed military personnel. The present study aimed to investigate the relationship between deployment-related stressors and symptoms of behavioral health concerns with affectivity among deployed U.S. service members. Participants were 1148 U.S. Air Force medical personnel deployed to Balad, Iraq, between 2004 and 2011. All participants completed self-report measures of PTSD symptoms, general military and combat exposure, stress, and affectivity. The Institutional Review Board at Wilford Hall Medical Center, the Air Force Personnel Survey Program, and the U.S. Army's Joint Combat Casualty Research Team reviewed and approved the study. Most respondents (89%, 1,018/1,139) reported a positive military experience, but many respondents reported exposure to a potentially traumatic event during deployment. For example, seeing dead or seriously injured Americans (47%, 523/1,123) was the most common exposure reported by participants. A large portion of personnel (21%, 232/1,089) reported clinical levels of PTSD symptoms (score of 33 or higher on the Posttraumatic Stress Disorder Checklist-Military version). Risk factors, including PTSD symptoms, combat exposure, and stress, explained 39% of the variance in negative affect, R2 = 0.39, F(1046) = 224.96, P < .001. Conversely, these risk and resilience factors, including PTSD symptoms, combat exposure, stress, and general military experiences, explained 28% of the variance in positive affect, R2 = 0.28, F(1050) = 103.79, P < .001. No significant gender differences were found between models predicting positive and negative affect. Negative mood states may be partly an epiphenomenon of PTSD, which has been shown to be safely and effectively treated in the deployed environment. Social support during deployments is uniquely associated with a positive mood. These findings extend beyond the military and into any high-stress occupation wherein leaders could interpret these findings as a need to build or reinforce efforts to provide opportunities to sustain healthy relationships in personnel. These critical indigenous resources support mission readiness and enable the maintenance of positive psychological health.