This book contains the papers presented at the NATO Advanced Study Institute held at Ustaoset H[cent]yfjellshotel, near Geilo, Norway, 24th April - 1st May, 1973. The members of the Programme Committee were J. D. Axe Brookhaven National Laboratory, USA J. Feder University of Oslo, Norway T. Riste Institutt for Atomenergi, Norway (Chairman) The title of the institute, "Anharmonic Lattices, Structural Transi tions and Melting", gives an idea of the programme and of the content of this book. The first part is devoted to the so- called "central mode" at 2nd order structural phase transitions, a phenomenon which was first reported in 1971 at a NATO Advanced Study Institute held at Geilo. (Several references to the pro- ceedings of that institute, entitled "Structural Phase Transitions and Soft MOdes", are found in the present volume). From 2nd order transitions the emphasis of the programme moves gradually to 1st order transitions by covering such topics as order-disorder structural transitions in simple molecular crystals and tricritical phenomena. The last part is devoted to melting, including dis- cussions on the dynamics of solids and liquids near their melting points. The lectures are divided almost equally between review talks and research reports dealing with subjects closely connected with the topics under review. With a few exceptions the lectures are printed in the sequence of presentation at the study institute. The total number of participants was limited to 71, their names are given at the end of the book.