In recent years, human hair has received considerable attention as a toxicological specimen for evidence of chronic drug use in clinical and forensic investigations. Compared with urinalysis, hair analysis has the potential for greatly expanding the time window for drug detection. In addition, sample acquisition for hair drug testing is less intrusive. This NIJ Report, Evaluation of Analytical Methodologies for Non-Intrusive Drug Testing: Supercritical Fluid Extraction of Cocaine from Hair, describes the results of the investigation of supercritical fluid extraction (SFE) as an environmentally "friendly" sample preparation method, which overcomes some of the limitations of currently used liquid-based hair drug testing methodologies while simultaneously contributing to a greater fundamental understanding of drug-hair binding mechanisms.