Electroencephalography is truly an interdisciplinary endeavor, involving concepts and techniques from a variety of different disciplines. Included are basic physics, neuro­ physiology, electrophysiology, electrochemistry, electronics, and electrical engineer­ ing, as well as neurology. Given this interesting and diverse mixture of areas, the train­ ing of an EEG technician, a neurology resident, or an EEG researcher in the basics of clinical electroencephalography presents an uncommon challenge. In the realm of technology, it is relatively easy to obtain a technically adequate EEG simply by learning to follow a protocol and by correctly setting the various switches on the EEG machine at the right time. But experience has shown that the ability to obtain high-quality EEGs on a routine, day-to-day basis from a wide variety of patients requires understanding and knowledge beyond what is learned by rote. Likewise, knowledge above and beyond what is gained by simple participation in an EEG reading is necessary to correctly and comprehensively interpret the record. Such knowledge comes from an understanding of the basic principles upon which the practice of clinical EEG is founded - principles that derive from the various disciplines cited.