The chapter critically reviews the literature that purports to establish the empirical association between alcohol or drug use and violence and also examines the available evidence for various explanatory models of the association. The empirical literature reviewed can be divided into three types of studies: (1) epidemiological studies based on offender and general population samples;(2) experimental studies that have examined the main effects of drugs and alcohol on aggression; and (3) multifactorial studies that have analyzed interactions and moderating variables in more complex causal models. Each of these approaches has inherent limitations; and it is only through summation and integration of these divergent approaches that progress is achieved in understanding the alcohol, drug, and violence etiological interaction. The chapter concludes that a simplistic model of the role of alcohol and drugs in the etiology of interpersonal violence can be rejected summarily; it is clear that alcohol and drugs are neither necessary nor sufficient to explain a violent act. The available evidence suggests a pharmacological role in violent events for alcohol and some benzodiazepines. Other drugs of abuse seem to be associated with violent events through nonpharmacological, systemic, and economic processes. Alcohol and its combination with other drugs may contribute to phenotypically diverse violent outcomes through complex causal pathways that involve activation of pre-existing biobehavioral dispositions and cognitive expectancies in particular situational circumstances. Finally, alcohol and drug variables apparently have promise in risk assessment frameworks, and knowledge from research on effective alcohol and substance-use treatment programs suggests their critical utility in the development of future violence risk-management approaches. 1 table and 105 references