Aims: To examine the quality of screening and assessment practices at some of the most highly regarded adolescent substance use treatment programs in the United States. Methods: Between March and September 2005, telephone surveys were administered to directors of highly regarded programs. Several different publications and databases were then used to measure the quality of the screening and assessment instruments described by programs. Results: For the 120 programs responding, 77 distinctly named instruments developed by outside sources were used at some point in the screening and assessment process, and the majority of programs also used instruments developed in-house. Fewer than half of these instruments were mentioned in the Substance Use Screening & Assessment Instruments Database. We were able to confirm that 87% of the instruments developed by others have a published manual, and 74% have been described in an article appearing in a peer-reviewed publication. Sixty-two percent were designed to be used with adolescents or adults and adolescents, while 19% were designed for adults only. Conclusion: Although adolescent substance abuse treatment programs recognized the importance of screening and assessment, the quality of such practices varied significantly. A large number of different tools were used by some of the most highly regarded programs in the country, and many used questionnaires developed in-house that may not have had high standards of reliability and validity. Furthermore, numerous programs were using assessment instruments that were not uniquely designed for adolescents. Encouraging the adoption of standardized assessment practices would help those involved in treatment to evaluate programs and to understand the assessment process. (Contains 2 tables.)