California has been a leader in the field of inmate drug treatment in terms of the number of programs implemented and the integration of in-prison treatment and community aftercare. California has 32 prison-based drug treatment programs, with funding for 6 months of community aftercare. Evaluations have played a crucial role in determining program directions. All of the California programs described in this issue's articles provided the opportunity for prison-based treatment participants to enter community treatment following release. The evaluation studies reported in this issue examined correctional programs that combined prison treatment with community treatment. Findings from these evaluations show that participation in both treatment phases is associated with better outcomes. The treatment modalities profiled are the modified therapeutic-community model and cognitive-behavioral approach. This introductory article advises that the issue in selecting treatment modality is its appropriateness for the type of client being treated. Further, this introductory article notes that the articles in this special issue highlight the contribution that research and evaluation can make to the design, implementation, and improvement of correctional treatment programs. Combining the knowledge and experience of the clinician with the theoretical insights and empirical findings of the researcher can lead to improvements in assessing and referring clients, retaining and engaging them in treatment, coordinating services, and supporting posttreatment recovery. 7 references