This book reflects debates and results which have developed since the introduction of an international system of classifications in epileptology. The creation of such a system was initiated, in the sixties, mainly for practical reasons: growing international exchange had revealed that divergence of terminology in epilepsy had become important enough to prove a serious obstacle to sensible discussions. The Bethel-Cleveland symposia, which was at the origin of this book, aim to bring the excellence of advanced inter-disciplinary and controversial workshops to a larger public. This book concentrates on a selection of topics where progress has been made, where controversies are open or where discussion needs to be stimulated.