Electron energy-loss spectroscopy (EELS or ELS) has been used to investi­ gate the physical properties of solids for over 40 years in a handful of laboratories distributed around the world. More recently, electron micro­ scopists have become interested in EELS as a method of chemical analysis with the potential for achieving very high sensitivity and spatial resolution, and there is a growing awareness of the fact that the loss spectrum can provide structural information from a thin specimen. In comparison with energy-dispersive x-ray spectroscopy, for example, EELS is a fairly demand­ ing technique, requiring for its full exploitation a knowledge of atomic and solid-state physics, electron optics, and electronics. In writing this book, I have tried to gather together relevant information from these various fields. Chapter 1 begins at an elementary level; readers with some experience in EELS will be familiar with the content of the first two sections. Chapter 2 deals with instrumentation and experimental technique, and should con­ tain material of interest to researchers who want to get the best performance out of commercial equipment as well as those who contemplate building their own spectrometer or electron-detection system. Chapter 3 outlines the theory used to interpret spectral features, while Chapter 4 gives procedures for numerical processing of the energy-loss spectrum. Chapter 5 contains examples of practical applications of EELS and a discussion of radiation damage, spatial resolution, and detection limits.