This is the first volume of a series on a regular up-to-date coverage of important developments in astronomy and astrophysics jointly published by ESO and Springer-Verlag. Here the reader finds a thorough review of the abundances of the elements up to Boron. Special emphasis is laid on primordial abundances of interest to cosmologists in particular, and on stellar production or destruction respectively. The articles written for researchers and graduate students cover theory and most recent data from telescope observations.