Written by leading experts in the field of band-ferromagnetism, this book is intended to give a status report on our understanding of this complicated and fascinating problem of solid state physics. Modern developments are presented and explained in a tutorial style, emphasizing the decisive ideas and the hot topics of current and future research on band-ferromagnetism. The authors include experimentalists and theoreticians working on different aspects of magnetism and employing a variety of techniques. In particular, they treat the following five central themes: Ground-State Properties, Finite-Temperature Electronic Structure, Models of Band-Ferromagnetism, Low-Dimensional Systems, Understanding Spectroscopies. The book will be of benefit to students and researchers alike.