This report describes and summarizes the activities during the third year of the program entitled, Quality Assurance in Support of Energy Related Activities. The activities reported cover the period from October 1, 1978 to September 30, 1979. The purpose of this program is to establish a quality assurance data base for ambient air monitoring in specified geographical areas around present and proposed energy development projects, and to provide technical assistance to enable monitoring networks to achieve a high level of data quality. Discussed in this report are the regularly scheduled Quality Control Reference Sample Audits conducted for the analysis of sulfate, nitrate, sulfur dioxide, nitrogen dioxide and carbon monoxide, and for weight measurement and high-volume flow rate. In these surveys reference samples or devices are submitted to participating laboratories and their results compared with those obtained by Rockwell. Performance results for the third year of the program have remained essentially constant for sulfate, nitrate, sulfur dioxide and carbon monoxide. The results for carbon monoxide are noteworthy for their consistently high quality. Results for nitrogen dioxide have shown some improvement, but do not continue the trend indicated in the last three audits of 1978. Improvements in performance have also been quite notable in the high-volume survey.