Auger electron spectroscopy combined with inert−gas ion bombardment is one of the accepted techniques for obtaining information regarding the depth distribution of elemental species in a variety of materials. The intent of this paper is to discuss in some detail the depth−profiling technique combining Auger electron spectroscopy and intert−gas ion bombardment. Special attention will be given to the basic considerations, problems, and limitations of the technique as well as the qualitative and quantitative information that may be obtained. Several applications of the technique will be presented for a variety of materials to demonstrate the wide−range application and practical utility of this method for depth profiling.