EPA promulgated minimum quality assurance (QA) requirements for Continuous Emission Monitoring Systems (CEMS) in 40 CFR Part 60 Appendix F. Appendix F requires the development of site-specific QA plans and the reporting of results of EPA specified QA activities each calendar quarter. The report of QA activities under Appendix F is called a Data Assessment Report (DAR). The DAR includes identifying and descriptive information for the CEMS, results of periodic audits, identification of periods when calibration drift exceeds specified criteria, identification of periods when the analyzers or CEMS are out of control (OOC), and descriptions of corrective actions in response to OOC conditions. The principle objective of the study is an evaluation of the information in DARs for the first and second quarters of calendar year 1988. Secondary study objectives include the establishment of contacts with agency staff who normally receive the DARs each quarter and identification of facilities for which DARs were apparently not received, for follow-up by the appropriate agency.