The primary objectives of this proposal are to develop objective pre-deployment predictors of PTSD and test two pre-deployment resiliency interventions. The objective predictors will be based on: 1) physiologic reactivity (heart rate, heart rate variability, eye blink startle, skin conductance) to virtual reality (VR) environments depicting common Operation Iraqi Freedom (OIF) or Operation Enduring Freedom (OEF) combat scenarios and 2) cognitive bias assessment using a recognition memory paradigm. We hypothesize that a model combining physiologic reactivity and cognitive bias predictors will be superior to either the physiologic reactivity or cognitive bias model alone for predicting post-deployment PTSD. We also will test two pre-deployment resiliency interventions: heart rate variability biofeedback and cognitive bias modification training that we have designed to target physiologic and cognitive responses to stress, respectively. We will compare the prevention interventions to a no intervention control group. We hypothesize that the prevalence of post-deployment PTSD will be lower in the intervention groups compared to the control group.