Approved for public release, distribution is unlimited / The purpose of this thesis was to examine the feasibility of testing hair for illicit drug use in the United States Marines Corps. Specifically, the study determined the hair test's potential for detecting and deterring illicit drug use and abuse among Marines. In addition, the study estimated the potential costs of implementing hair tests and examined fairness concerns with regard to testing hair among ethnically diverse populations. The results indicate that the hair test would be more effective than the urinalysis at detecting a wide variety of illicit drugs, with the exception of marijuana. The increased effectiveness of the hair test is likely to enhance the level of deterrence currently sustained by the Marine Corps' urinalysis program. Costs associated with the implementation of hair test would be offset by the increase in detection of illicit drug use and drug dependence among enlisted recruits and officer candidates pursuing active duty military service. Enhanced deterrence levels among active duty personnel that are a consequence of implementing the hair test would result in additional cost savings. Finally, implementation of the hair test would not result in racial bias, but may amplify the existence of drug preferences among different races. / Major, United States Marine Corps