Your team has limited understanding of the system, and unit tests are missing for many, if not all, of the component. How do you reduce the complexity of legacy systems enough so that it can continue to be used and adapted with acceptable cost? Based on industry experience of the authors', this book is a guide on how to reverse engineer legacy systems to understand their problems, and then reset the system to meet new demands. The main understanding is that the right design and organization of your system is not something that can be proven from the initial conditions alone, but as a result of understanding how requirements evolve. * Explains how to reverse engineer a monolithic system to understand how it actually works and how to identify potential problems. * Includes reengineering patterns that overcome the well-known re-engineering techniques often encountered in object-oriented programming, such as introducing polymorphism, factoring out common behavior, detecting duplicated code, and design comprehension. * Shows how to build a culture of continuous re-engineering to achieve a flexible object-oriented systems and maintained.