The report was prepared to aid in planning a program to standardize methods of source measurement used in air pollution control. Many differences exist between methods used for ambient air measurement and source measurement, related to the differences in concentration, temperature and humidity of the sample streams, interferences that affect analytical results, and other factors. The differences in the two types of methods have been substantial, therefore results obtained with these different methods likely are not equivalent. Emission standards have little meaning unless a method of measurement is specified, and specific methods or general guidelines have usually been published with such standards. The need for a standardization program is outlined.