The initial phase of substance abuse treatment is a vulnerable period for relapse. Cognitive impairments are common during this phase and may reduce the ability to benefit from other forms of substance abuse and rehabilitation services. The study compares a rehabilitation program that combines work therapy with computer-based cognitive training of attention, memory and executive functions to work therapy alone in a 3 months outpatient substance abuse program. It is hypothesized that cognitive training will increase days of sobriety during the active intervention and better substance abuse outcomes at 6 month follow-up.