The nine editions of Stable Isotope Geochemistry have appeared over a time span of nearly 50 years. The first edition (1973) appeared as a slim book of 135 pages. Due to the rapid development of the field, extended editions became necessary from time to time. The first 4 editions centered on the classical light elements, so-called CHONS. From the 5th edition 2004—with the introduction of the Multicollector-ICP-Mass Spectrometry—the book had to be enlarged, because many more elements—47 elements in the 9th edition—can be measured with the necessary high precision. The increase of the number of elements, together with advances in the calculation of equilibrium isotope fractionation using ab initio methods, has led to an unbelievable rise of publications, making again a rewriting with substantial major revisions and extensions necessary. To follow the recommendations of the International Union of Pure and Applied Chemistry (IUPAC), the term dD has been replaced by d2H in the new edition. The general structure of the book has been kept. Chapter 1 gives a general introduction to the theoretical and experimental principles. Chapter 2 is divided in two parts: Part I discusses the “traditional” elements hydrogen, carbon, oxygen, nitrogen, and sulfur measured by gas-source mass-spectrometry. Part II presents the “non-traditional isotopes”, measured predominantly by multi-collector inductively coupled mass-spectrometry. At places elements with close geochemical relationships are discussed successively. Chapter 2 gives an overview of natural isotope variations of 47 elements; Rb, Zr, and Nd, Eu and the HREE have been added in the new edition. Special emphasis has been given to studies that have been published over the last three years, while still summarizing the important discoveries made before that time. As in earlier editions, the third part discusses natural variations of isotope compositions in the context of the classic geochemical “spheres”. New subsections have been added such as: Meteorite-Earth relationships, volatile elements on the Moon, magnesium and iron relationships in magmatic rocks, subduction-zone metamorphism, metal isotope variations in ore deposits and in the ocean, and carbon isotope stratigraphy. Chapter 3 ends with two new subtitles:(i) forensic isotope geochemistry and (ii) medical investigations. A very long list of references with many new citations enables a quick access to the exponentially growing recent v