A definition of drugs emphasizes that the pharmacological aspects of drugs are only one feature of the drugs-violence connection; also central are the costs of drugs, how they are obtained, how they are ingested, and the social contexts of both drug use and drug distribution. The author notes the longstanding limited quantity and quality of data on the drug-violence connection and the reasons for this deficiency. The studies reviewed indicate a strong relationship between drugs and violence. The chapter presents a "tripartite" framework for understanding the relationship between drugs and violence: psychopharmacological components, economical compulsivity aspects, and systemic elements. The first approach acknowledges the neurophysiological components of violence and how drugs can influence violence through biological modalities. The second approach notes that some drug users engage in economically-oriented violent crime to support costly drug use. The third approach recognizes that violence is an integral component of the organizational structures and market strategies of illicit drug distribution and use. 9 notes, 106 references.