According to the 2008 Department of Defense Survey of Health Related Behaviors among Active Duty Military Personnel, 2.3 percent of military personnel were past-month users of an illicit drug, compared with 12 percent of civilians. A policy of zero tolerance for drug use among DoD personnel was instituted in 1982. However, in spite of the low level of illicit drug use, abuse of prescription drugs is higher among service members than among civilians and is on the increase. In 2008, 11 percent of service members reported misusing prescription drugs, up from 2 percent in 2002 and 4 percent in 2005. Most of the prescription drugs misused by service members are opioid pain medications. Those with multiple deployments, combat exposure, and related injuries are at greatest risk of developing substance use problems. They are more likely to engage in new-onset heavy weekly drinking and binge drinking, to suffer alcohol and drug related problems, and start smoking or relapse to smoking. NIDA continues to examine the trends in substance use in specific populations, including military personnel, and search for better methods for preventing and treating substance use disorders that are specific to these populations.