Interviews were conducted with 18 crack-using respondents from the Alameda County, Calif., Methadone Study, a longitudinal study of a new maintenance policy that limits county support for an individual's treatment. The rule requires that after 2 years in treatment, individuals must "detox off" the program or begin paying as a private patient at $200 per month. Interviews showed that the availability of cocaine has contributed to the increasing involvement of opiate users, including methadone clients, with cocaine. Aside from the allure of cocaine's euphoria-inducing properties, its availability and relatively low cost make cocaine especially tempting. The use of crack and powder cocaine has increased by heroin users in inner cities. The overlap of heroin and cocaine consumption tends to be self-reinforcing. Because methadone cannot block the effects of cocaine as it does opiates, crack is appealing to some individuals on methadone maintenance. Smoking "rocks" eliminates the need for an outfit, spares the user fresh needle marks and the possibility of a heroin-positive urine test, and momentarily obviates the temptation of returning to heroin use. The authors conclude that the 2-year rule in Alameda County drives people back to illicit drug use. Since most clients do not have the money to pay the $200 per month fee, they are forced to return to street life and become exposed to the danger of acquiring a dual addiction to heroin and crack. 10 references.