Drug abuse treatment programs need to know the cost of the services they provide. Indeed, continued public and private funding is now being linked to cost and performance measures, and programs can use financial data to improve organizational efficiency. However, one of the dangers of promoting cost studies at treatment programs is that most program staff are not technically prepared to perform a cost analysis and little user-friendly information is available to offer assistance. Furthermore, not all cost methods are consistent, which can lead to noncomparable estimates that are difficult to use for policy or planning purposes. Our paper tries to fill this gap in the research literature and provide treatment programs with a much-needed technical assistance tool. Specifically, we present a structured and scientifically-based instrument for estimating the economic cost of treatment services. The Drug Abuse Treatment Cost Analysis Program (DATCAP) is described in detail along with a companion instrument to analyze treatment financing; the Drug Abuse Treatment Financing Analysis Program (DATFin). The components of both instruments are outlined and findings from a variety of actual case studies are presented. Lastly, we discuss the DATCAP User's Manual, which will enable individual programs to begin collecting the necessary data and estimating economic costs at their own clinics.