First published in 1980, this is a Festschrift to honour Professor David Schoenberg, FRS, on the occasion of his retirement from the Cavendish Laboratory, Cambridge, in 1978. Written by his students, colleagues and friends, it is devoted to the theme of electrons at the Fermi surface. The book is arranged in three parts of which the the first is concerned with certain general and fundamental issues. Part II relates more specifically to electronic structures and to Fermi surfaces, not simply to their important topological features and intriguing shapes, which give much delight, but rather to the information on the related ground state and elementary excitations of the system to which their study gives access. The final part is concerned exclusively with certain aspects of the de Haas-van Alphen effect. The book will interest both experimental and theoretical solid-state physicists concerned with the electronic properties of metals and alloys.