In Volume IIC of the series, G.L. Macdonald contributed a chapter on X-Ray Spectrometry in which the principles of X-ray fluorescence analysis were presented with great clarity. Since that contribution appeared in 1971 tremendous developments have taken place with one of the most important new features being the appearance of energy-dispersive methods.This new volume gives a detailed and up-to-date account of this important technique. It covers the various physical and technical problems associated with this analytical method, with emphasis on explaining the interferences due to matrix and particle size effects. Methods for overcoming these interferences are described and other sources of errors and the processing of measurement data are discussed. Also described are numerous applications of EDXRF analysis in a variety of fields including geological prospecting and mining, trace element analysis, biology, medicine, environmental pollution control, archaeology, forensic sciences, and others.