The census instrument collected information on program content and structure (e.g., program type, duration, and primary treatment approach); program staff (e.g., duties and staffing ratios); and inmates (e.g., eligibility and intake procedures). The census respondents were personnel responsible for directing the treatment programs at each of the 24 facilities. Researchers also conducted in-depth process evaluations at two institutions selected by the steering committee. Both institutions provided a full range of treatment services. The study found that in programs that involved a therapeutic community (TC), there was a high level of consistency. Within other program types, the study found considerable variation on such variables as program duration, intensity, and staffing; target selection criteria; and program placement decisions. The evaluation recommends that correctional agencies make greater use of standardized instruments for screening inmates' level of need for treatment, readiness for treatment, and psychological functioning. It also recommends the development of information system capacities pertinent to offender program participation and the examination of programming priorities and resources required for prison-based drug treatment programs. 11 notes and 61 references