Efforts to control illegal drug use and the international narcotics trade concentrate on interdiction. Empirical evidence discloses that these efforts have largely failed. The crucial question for policymakers seems to be ignored: Can interdiction succeed as a means to control drug traffic and use? A dynamic model of the illegal drug business indicates that feedback mechanisms exist that will thwart interdiction efforts by stabilizing price and street supply. The model suggests that efforts to control drug traffic and disrupt international drug cartel operations should concentrate on money flows and reduction of demand. It also suggests how to maximize the effect of interdiction, should that still be used as a strategy.