This classic textbook is an introduction to the systematics and the use of stable isotopes in geosciences. It is subdivided into three parts: i) theoretical and experimental principles, ii) fractionation processes of light and heavy elements, iii) the natural variations of geologically important reservoirs. Since the publication of the previous edition advances in multicollector-ICP-mass-spectrometry allow precise measurements of new isotope systems. In this new edition therefore, 42 elements with resolvable natural variations in isotope composition are discussed. New findings from non-traditional isotope systems have been incorporated. Many new references have been added, which enable quick access to recent literature.