This letter provides GAO's response to the Public Company Accounting Oversight Board's (PCAOB) Release 2015-005, Concept Release on Audit Quality Indicators. GAO promulgates generally accepted government auditing standards (GAGAS) in the United States. GAGAS provide a framework for conducting high-quality audits of governments and other entities expending government funds. Depending on how the concepts illustrated in this release are implemented, an audit quality indicator (AQI) project could set a precedent for how audit quality is assessed well beyond the audit environment under the PCAOB's purview. AQI-based auditor evaluations could become an industry-wide expectation for auditors of many types of organizations, including those subject to GAGAS audits.