Of all the various methods available to measure atmospheric particle contaminants, the so-called High Volume Method (frequently called 'Hi Vol' Method) has probably been used more extensively than any other. Since no standardized procedure has been available to guide different laboratories in the use of this method, each laboratory has had to develop and evaluate different techniques. The report presents the results of a collaborative test of the High Volume Method. A statistical analysis of the data obtained provided the following results: The relative standard deviation for single analyst variation; The relative standard deviation for multilaboratory variation is 3.7 percent; and the minimum detectable amount of particulate matter is 3 mg (95 percent confidence level). The method is rugged, and variations in procedure and technique can occur with only a minor effect on the results.