Using data from the National Criminal Justice Treatment Practices (NCJTP) Survey, estimates of offenders participating in drug treatment services were generated. Existing drug treatment programs have a capacity to serve around 10 percent of offenders. The majority of available services are alcohol and drug education and group counseling, which are suited for people with low-threshold substance use disorders. Yet a third of the offenders are reported to have a severe disorder (dependency) requiring more intensive structured services. Offenders in prison and jail are more likely to have access to treatment services compared to offenders in the community. Regardless of the correctional setting, only a small portion of the offender population receives the appropriate level of treatment. The current delivery system is inadequate to reduce the risk of recidivism. Using the risk, need, and responsivity framework to address the adequacy of dealing with drug-involved offenders, the current service delivery does not embrace this model. An effective correctional system should not only expand treatment capacity but also provide appropriate services given the needs of offenders. The composition of the current system demands attention to providing more intensive services to effectively use resources and to focus on risk reduction strategies. Abstract published by arrangement with Taylor and Francis.