X-ray fluorescenct" spectrometry is now widely accepted as a highly versatile and potentially accurate method of instrumental elemental analysis and so it is somewhat surprising that although the volume of published work dealing with the technique is high the number of textbooks dealing exclusively with its application is relatively few. Without wishing to detract from the excellence of the textbooks which are already available we have both felt for some time, that a great need exists for a book dealing with the more practical aspects of the subject. For a number of years we have been associated with the provision and arrangement of X-ray schools for the training of new X-ray spectroscopists as well as in the organisation of conferences and sym­ posia whose aims have been to keep the more experienced workers abreast with the latest developments in instrumentation and techniques. In all of these ventures we have found a considerable dearth of reference work dealing with the reasons why an X-ray method has not succeeded as opposed to the multitude of success stories which regularly saturate the scientific press. In this book, which is based on lecture notes from well established courses in X-ray fluorescence spectrometry, we have tried to cover all of the more usual practical difficulties experienced in the application of the method and we have endeavoured to keep the amount of purely theoretical data at a minimum.