Principles of Peptide Synthesis is a very successful book by one of the pioneers of contemporary bioorganic synthesis. Its first edition proved a valuable source that is kept close to the work bench for frequent consulting. Any researcher planning the formation of the peptide bond, be it for the synthesis of a peptide chain or a cyclic peptide, benefits from the author's experience. The concise and critical treatment of the steps involved: protection, activation and bond formation require careful planning to avoid racemization and undesired side reactions. The second edition has been completely revised and updated. New procedures that have been developed since the first edition was published and that did not fit into the original are added in a separate chapter. This separation of old and new make it possible to assess new ideas and discern novel trends.