We are very pleased to present the Second Edition of Elements of Propulsion: Gas Turbines and Rockets by Jack D. Mattingly. The original edition was a well-received, comprehensive, and in-depth treatment of these important topics. This new edition has updated the material and expanded the coverage, and we anticipate that it will be equally well received. An interesting feature of the first edition was a very extensive foreword by the jet engine pioneer, Hans Von Ohain. Indeed, it is so extensive and comprehensive that it is more a historical overview and introduction than a foreword. We deem it so useful that it is included in this edition as well. This Second Edition has ten chapters, seven appendices and more than 850 pages.