The present book is the second edition of Amikam Aharoni's Introduction to the Theory of Ferromagnetism, based on a popular lecture course. Like its predecessor, it serves a two-fold purpose: First, it is a textbook for first-year graduate and advanced undergraduate students in both physics and engineering. Second, it explains the basic theoretical principles on which the work is based for practising engineers and experimental physicists who work in the field of magnetism, thus also serving to a certain extent as a reference book. For both professionals and students the emphasis is on introducing the foundations of the different subfields, highlighting the direction and tendency of the most recent research. For this new edition, the author has thoroughly updated the material especially of chapters 9 ('The Nucleation Problem') and 11 ('Numerical Micromagnetics'), which now contain the state of the art required by students and professionals who work on advanced topics of ferromagnetism. From reviews on the 1/e: '...a much needed, thorough introduction and guide to the literature. It is full of wisdom and commentary. Even more, it is Amikam Aharoni at his best - telling a story...He is fun to read. ..The extensive references provide an advanced review of micromagnetics and supply sources for suitable exercises...there is much for the student to do with the guidance provided by Introduction to the Theory of Ferromagnetism.' A. Arrott, Physics Today, September 1997.