This volume comprises papers presented at the 2005 edition of the Crystallography of Molecular Biology courses that have been held since 1976 at the Ettore Majorana Centre for Scientific Culture in Erice, Italy. This series of courses is renowned for bringing leaders in the field of macromo- cular crystallography together with highly motivated students, in a beautiful and intimate location that encourages people to interact. The warm and informal atmosphere at these Erice conferences, especially these on cryst- lography, has helped to foster long-term scientific interactions and new int-...