The intent of this work is to bring together in a single volume the techniques that are most widely used in the study of protein stability and protein folding. Over the last decade our understanding of how p- teins fold and what makes the folded conformation stable has advanced rapidly. The development of recombinant DNA techniques has made possible the production of large quantities of virtually any protein, as well as the production of proteins with altered amino acid sequence. Improvements in instrumentation, and the development and refinement of new techniques for studying these recombinant proteins, has been central to the progress made in this field. To give the reader adequate background information about the s- ject, the first two chapters of this book review two different, yet related, aspects of protein stability. The first chapter presents a review of our current understanding of the forces involved in determining the conf- mational stability of proteins as well as their three-dimensional folds. The second chapter deals with the chemical stability of proteins and the pathways by which their covalent structure can degrade. The remainder of the book is devoted to techniques used in the study of these two major areas of protein stability, as well as several areas of active research. Although some techniques, such as X-ray crystallography and mass spectroscopy, are used in the study of protein stability, they are beyond the scope of this book and will not be covered extensively.