With more than 20 years of experience in the teaching of mass tral interpretation to chemists in the health, environmental, and forensic fields, R. Martin Smith has done an excellent job (with the help of Prof. Ken Busch as technical editor) with this introductory book on mass spectrometry (MS) and spectral interpretation. Rather than attempt to cover the entire field, he focuses on electron ionization (EI), instruments that use this ionization technique, and the spectra that result. In writing a book on EIIMS, it is very difficult to not be, in some way, derivative of Fred McLaffeity's Interpretation of Mass Spectra, historically the most important book in this field to date. Smith covers the basics, creates new “basics,” and offers a text that will be conlpetitive with the best. Understanding Mass Spectra contains chapters on “Isotopic Abundances,” “Ionization, Fragmentation and Electron Accounting,” “Neutral es and Ion Series,” “Alpha-Cleavage,” and “Important Mass tral Reairangements,” the key topics of this field. However, h's work also offers unique and important chapters such as riting Mass Spectral Fragmentation Mechanisms” and “Structure Determination in Complex Molecules Using Mass trometry.”