The legitimacy of social work as a scientific discipline, and as a profession, cannot be ensured without taking into consideration a basic characteristic of contemporary scientific and technological systems: the evaluation of results. In our field, this involves evaluating new knowledge, new practical applications, and also new systems of evaluation to improve the services we provide and better allocate public and private resources. The social work discipline and profession must meet the standards of quality demanded of science in advanced democratic societies, where accountability is a necessary condition to obtain funding. At the same time, by innovating our discipline we can provide better services to citizens, manage resources more effectively and, above all, evaluate the results in order to achieve sustainable well-being in the medium and long term. Research, innovation and evaluation unquestionably constitute some of the hallmarks of 21st-century social work. In this sense, the contributions of this book endeavor to advance the development of research as an essential element for the progress of the science of social work and its practical application.