This book was written to be an introduction to the science of amorphous materials. It is aimed at final year undergraduates, beginning graduate students and researchers in solid-state physics or chemistry, materials science or engineering. Some background of (crystalline) solid-state physics is assumed, say between the levels of Kittel's "Introduction to Solid-State Physics" and Ziman's "Principles of the Theory of Solids", because the authors felt that in a book this length such background materials could not easily be incorporated; however, no knowledge of amorphous materials is assumed. Knowledge about the state of matter has changed considerably since the first edition of this book was published. In part this was due to discoveries, such as the discovery of icosahedral (quasicrystalline) phases in certain metalloid alloys therby forming a bridge between the perfect cyrstalline and the topologically disordered state, but mostly advances have come through a steady application of experimental techniques, both old and new, and the further development of theoretical ideas. The overall structure of the book has been changed slightly by distributing the material relating to amorphous metals throughout the text where appropriate, rather than including it in a separate chapter as in the previous edition. A final chapter on some technological applications of amorphous materials has been added in its place. The chapter on structure has been extensively rewritten, incorporating the significant new results which have appeared in the recent years. Chapter four on atomic dynamics has also been extensively modified, principally by the incorporation of an expanded section on ionic transporton glasses. In addition, recent advances in all areas of glass science have been included throughout the book, and about 400 new references to work in the literature have been added.