Although there are limitations in the data available for analysis, evidence indicates that persons who engage in drug trafficking and those who use drugs are more likely to commit crimes, that arrestees are often found to be under the influence of drugs at the time they commit their offenses, and that drugs tend to generate violent responses and behaviors. Evidence regarding the drug-crime link remains problematic, however, such that any quantitative certainty about the exact impact of drugs on crime is not currently possible. One section of this chapter focuses on trends in drug trafficking and use compared with trends in violent crime. Studies that have focused on this issue are reviewed. The author notes that there appears to be a correlation between the increases in drug abuse that coincide with the emergence of crack cocaine and increases in violent crimes, notably aggravated assault and robbery; however, although stabilization has occurred in violent crimes, the trend line for drug abuse has remained significantly above the initial 1980 data. A review of current drug trends among young adults focuses on club or designer drugs and opiate substances. Overviews of these drugs, including cannabis, are presented. The chapter then turns to drug treatment, as it focuses on risk factors believed to accentuate the potential for juvenile delinquency and violence. The chapter contains sections on a history interview prior to treatment and program design for effective interventions. Concluding sections of the chapter discuss delinquency myth versus reality regarding juvenile violent crime and the influence of biological factors on delinquency. 4 figures and 73 references