The Marine Corps Operational Stress Control and Readiness (OSCAR) program is designed to provide mental health support to marines by embedding mental health personnel within Marine Corps units and increasing the capability of officers and senior noncommissioned officers to improve the early recognition and intervention of marines exhibiting signs of stress. The Defense Centers of Excellence for Psychological Health and Traumatic Brain Injury have asked RAND to evaluate the OSCAR program. As part of this evaluation, RAND conducted a large survey of marines who were preparing for a deployment to Iraq or Afghanistan in 2010 or 2011. This article describes the methods and findings from this survey. The results are among the first to shed light on the pre-deployment mental health status of marines, as well as the social resources they draw on when coping with stress and their attitudes about seeking help for stress-related problems. The 2,620 marines in the survey sample had high rates of positive screens for current major depressive disorder (12.5 percent) and high-risk drinking (25.7 percent) and reported having experienced more potentially traumatic events over their lifetime than adult males in the general population. Marines in the sample also reported relying on peers for support with stress and perceiving moderate levels of support from the Marine Corps for addressing stress problems.