During past years many countries constructed large accelerators for investigating heavy ion collisions, and new theoretical techniques for analysing results and making predictions were developed. Semi-classical methods were studied in the early days of quantum mechanics. Their application to heavy ion collisions has led to new advances and a number of different schools have grown up, each one emphasising different aspects of the theory. The aim of this book is to present a unified treatment of various lines of development. This book will be of great interest to graduate students wishing to learn about semi-classical methods in nuclear physics and to theoretical and experimental nuclear physicists, especially those working in heavy ion physics. It will also be of interest to research workers in other areas, such as atomic physics and quantum chemistry, where similar techniques are used.