The paper discusses the major role played by quality assurance (QA) in the environmental engineering research programs conducted by EPA's Air and Energy Engineering Research Laboratory (AEERL) in Research Triangle Park, NC. Consistent with Agency policy, AEERL requires that all data collection be documented by approved QA Project Plans, which establish the data quality needed for a project. AEERL has developed an innovative Project Category approach to QA plan documentation which bases the mandatory reporting elements on the type of research project and the intended use of the data (e.g., rulemaking, fundamental research). This approach is also applied to audits, which ensure that QA requirements are implemented properly. AEERL has implemented a comprehensive QA program based on detailed QA Project Plans, QA audits, and final report reviews which can be readily adapted to other environmentally related, data collection activities at the Federal, State, and local levels.