The Health Related Behaviors Survey HRBS is the U.S. Department of Defenses flagship survey for understanding the health, health-related behaviors, and well-being of service members. Originally implemented to assess substance use i.e., illicit drugs, alcohol, and tobacco,the survey now includes content areassuch as mental and physical health, sexual behavior, and post deployment problemsthat may affect force readiness or the ability to meet the demands of military life. The HRBS is intended to supplement administrative data already collected by the armed forces. In 2014, the Defense Health Agency asked the RAND Corporation to review previous iterations of the HRBS, update survey content, administer a revised version of the survey, and analyze data from the resulting 2015 HRBS of active-duty personnel. The 2015 HRBS included U.S. Air Force, Army, Marine Corps, Navy, and Coast Guard personnel, and this report details the survey methodology and results.