This is the third volume of a four-part series on addictive behavior and specifically deals with illicit drugs. The pathways from initiation to drug abuse toward chronic and acute diseases and the process of addiction to illicit drugs will be explored. This requires a multi-disciplinary approach as the causes, consequences, and remedies of drug abuse as a behavioral disease are multi-disciplinary in origin. An in-depth psychological analysis of the relationship of drug use and the quality of life is followed with an analysis of the possible treatment of drug abuse and possible economic and legal remedies. The consequences of present policies are explored, and a possible alternative viable legal framework is discussed. Finally, a proposal for a regulated market for drugs is made.