The book’s content is based on lectures for the specializations “Protein Engineering” and “Medical Biotechnology” within the Master’s curriculum in “Biotechnology.” The lectures have been held at the University of Natural Resources and Life Sciences, Vienna, in cooperation with the Medical University of Vienna, since 2012 and are continuously adapted to reflect the latest developments in the field. The book addresses Master- and PhD students in biotechnology, molecular biology and immunology, and all those who are interested in antibody engineering.