Despite evidence that treatment is effective in reducing recidivism among inmates with substance use problems, scarce resources mean that few of those in need of treatment actually receive it. Computerized substance abuse interventions could be used to expand access to treatment in prisons without placing an undue burden on resources. The major aim of the study was to compare treatment conditions in terms of their service utilization, skills acquisition, and treatment satisfaction. The study recruited men and women with substance use disorders from 10 prisons in 4 States. In an open label clinical trial, 494 subjects were randomly assigned either to the Experimental condition, a computerized drug treatment intervention, the Therapeutic Education System (TES; n=249), or to the Control condition, Standard Care (n=245). Chi-square tests compared groups on categorical variables and independent samples t tests were used for interval level continuous variables. Initial evidence demonstrated: (1) comparable group rates of session attendance and high rates of TES module completion for experimental subjects; (2) comparable group gains in the development of coping skills; and (3) a more favorable view of TES than of Standard Care. Collectively, these results show that a computerized intervention, such as TES, can be implemented successfully in prison. Given the barriers to the delivery of substance abuse treatment typically encountered in correctional settings, computerized interventions have the potential to fill a significant treatment gap and are particularly well suited to inmates with mild to moderate substance use disorders who often are not treated. Abstract published by arrangement with Springer.