In a word: Salih N. Neftci's `Principles of Financial Engineering' is a triumph. Neftci's `Principles' joins Mason and Merton's "Cases in Financial Engineering" as the field's premier fundamental texts, most especially for students, but of practical use for practitioners as well. Neftci's chief strength in this work is the same that has made his "An Introduction to the Mathematics of Financial Derivatives" deservedly famous: clarity. Where other authors get bogged down in dark obscurantism, such as Beaumont's unsatisfying and inadequate "Financial Engineering Principles," or Galitz's risk management book, inappropriately titled "Financial Engineering: Tools and Techniques to Manage Financial Risk," Neftci sheds clear sunlight on the field of constructing structured products with the building blocks of financial instruments. He is the most gifted writer in practical financial mathematics, and his legions of fans are not wrong: there is no one better than Neftci at breaking down complex concepts in clear, digestible bites and then reassembling the whole. Neftci's `Principles' improves upon, and indeed replaces, Cuthbertson and Nitzsche's "Financial Engineering: Derivatives and Risk Management" for applicability and lucidity, and replaces Mashall's "Financial Engineering: A Complete Guide to Financial Innovation" in scope. But Neftci does not sacrifice addressing difficult or complex structures through useless over simplicity, as sadly is the case with Eales's "Financial Engineering," rather he builds his explanations smoothly and logically, shedding light on the topics at hand by continually clearly demonstrating a replicating portfolio that mimics the instrument using other asset classes. For example, he begins by addressing the construction of cash flows with forward contracts, and then moves on to interest rate derivatives, swaps, repos, and then puts them all together for dynamic replication methods and the construction of synthetics. Each chapter builds and sheds light on the next instrument and technique. By the time Neftci addresses options and applications to bond convexity strategies and credit derivatives, we are in a position of strength. Most notable is Chapter 14, which clearly reviews volatility trading and discusses both the strengths and pitfalls, before turning to the nearly endless problem and opportunities of volatility smiles. He does not turn away from the problem of pricing in the presence of smiles, and uses the example of trading in the FX markets to shed light on strategies. For those working on synthetic and structured products desks, this will be the premier text. For those working on credit derivatives and other derivatives desks, this work assists in clarifying basic financial engineering concepts that then are more appropriately addressed in specialized texts, Schönbucher's "Credit Derivatives Pricing Models," for example. For those seeking a more rigorous mathematical foundation to financial engineering, Capinski & Zastawniak's "Mathematics for Finance: An Introduction to Financial Engineering" or the works of Steven Shreve and Ioannis Karatzas are the volumes to turn to. But for a solid work for a student who wishes to be a practitioner, Neftci is always the first choice. For the instructor, this book, coupled with the above-mentioned `Cases' will provide the exact balance between techne and arte that provides students with the best education for engineering structured products. There is a single caveat to my otherwise wholehearted praise for this book: those already deeply familiar with these topics will find little new here: this is not a groundbreaking work announcing new techniques or research. Rather, the strength of Neftci's `Principles' again is clarity clarity clarity. This is a most welcome volume, the one I wish I had had as a graduate student, which leaves this reviewer envious of those who will benefit and have stronger careers due to its current availability. We owe Neftci our thanks.