The closing years of the 19th century and the start of the 20th century witnessed the emergence of microbiology and immunology as discrete sci- tific disciplines, and in the work of Roux and Yersin, perhaps the first benefits of their synergy—immunotherapy against bacterial infection. As we advance into the new millennium, microbiology and immunology again offer a c- ceptual leap forward as antibody phage display gains increasing acceptance as the definitive technology for monoclonal production and unleashes new - portunities in immunotherapy, drug discovery, and functional genomics. In assembling Antibody Phage Display: Methods and Protocols, we have aimed to produce a resource of real value for scientists who have followed the development of phage display technology over the past decade. The founding principles of phage display have always held an elegant simplicity. We hope that readers will find similar clarity in the technical guidance offered by the book’s contributors. In meeting our objectives, we have tried to cover the broad scope of the technology and the key areas of library construction, scre- ing, antibody modification, and expression. Of course, the technology cont- ues to advance apace, but we trust that readers will be able to gage the potential of phage display from our coverage, that some of its subtleties will emerge, and that our selection of methods will prove appealing. We are indebted to all the contributing authors for sharing their expertise with the wider scientific community.