This volume is a comprehensive and up-to-date compendium of worldwide experimental programmes dedicated to the pursuit of atomic mass measurements. A tutorial section includes the various fields of physics in which atomic masses play an important role: nuclear physics, quantum electrodynamics, stellar nucleosynthesis, and weak interaction studies. There is a section devoted to theoretical approaches for both atomic and nuclear interactions, as well as a host of new projects for further advancing the field. This volume presents both an introduction and review of the state-of-the-art concerning mass measurements, evaluation, and prediction.