The software development has changed dramatically the last decades. Software was primarily built in-house aiming to fit the needs of the users. During the 80's this tendency changed with the foundation of software houses specializing in the development of "off the self" software. The last years, the explosion of the internet usage has transferred many applications to the "cloud," making them accessible by everyone. However, no matter what the advances are, tailored software is still required. Organizations, like businesses and institutions, with a variety in characteristics will always have a need for a customized system that fits their needs. Therefore building software has become more complex not in terms of available technological solutions but in terms of determining user needs. There are still excellent robust software systems that solve the wrong problem. Therefore, enriching software engineering processes with business modeling methodologies has been one way to cope with this problem. In this book, we try to combine DEMO and RUP in order to exploit the advantages of both which will ultimately assist practitioners in the development of quality software.