Several basic psychological hypotheses about multiple drug abuse are examined, i.e., social determinants, the effect of availability on extent of abuse, that drug abuse is a symptom rather than a disease, the relationship of social class to psychopathology, the lack of specificity of psychodynamics or psychopathology to drug choice, and the use of drugs to facilitate or obliterate concern with assertion, relieve neurosis, or provide homeostasis. There is a need for a variety of comprehensive, directive treatment approaches from which an individual treatment plan can be chosen. Such plans must consider which of the complex factors that can lead to multiple drug abuse are most prominent and can be remedied in each case.