Abused arylalkylamines fall into two major categories: the indolealkylamines, and the phenylalkylamines: These agents can be further subclassified on the basis of chemical structure. Examples of these agents possess hallucinogenic, stimulant, and other actions. Drug-discrimination techniques have been used to classify and investigate this large family of agents. Such studies have allowed the formulation of structure-activity relationships and investigations of mechanisms of action. Arylalkylamine designer drugs also possess the same or a combination of actions, and are being investigated by the same methods.