Licensing and accreditation are widely used to improve and convey organizational quality. The objective of this study was to provide substance abuse treatment stakeholders with better evidence about how well licensing and accreditation actually correlate with staffing and treatment practices. Regressions using data from national surveys of outpatient substance abuse treatment facilities indicated that no form of licensing or accreditation was associated with better staff-to-client ratios or with one important aspect of comprehensive treatment-the percentage of clients receiving routine medical care. There were several positive associations between licensing/accreditation and other aspects of treatment comprehensiveness. Three categories of licensure/accreditation were also positively associated with use of after-treatment plans. Post hoc analyses revealed that accreditation was associated with units' organizational contexts and referral sources as well as the nature of the competitive environment. Licensing/accreditation may reveal as much about units' institutional environments as about the quality of treatment provided. © 2007 Elsevier Inc. All rights reserved.