This volume is a collection of lectures presented during the 2009 International School on High-pressure Crystal- graphy, which took place at the Ettore Majorana Center for Scientific Culture, between June 4 and 14, 2009, in the very picturesque Sicilian town of Erice. st The 2009 school was the 41 course of the "International School of Cryst- lography" organized at the Majorana Center and was directed by Elena Figure 1. Audience, including local Boldyreva (Novosibirsk University) organizers (orange scarfs) and student and Przemyslaw Dera (University of participants during one of the lectures. Chicago). Unmatched support and excellent on-site organization was provided by the expert team consisting of Prof. Paola Spadon (Uniersity of Padova), Prof. Lodovico Riva di San Severino (University of Bologna), Elena Papinutto and Prof. John Irvin (University of California, San Franciso), aided by great team of young local organizers ("orange scarfs"). Major part of funding for the school was provided by a grant from the NATO Science for Peace and Security program, through which the 2009 Erice school was recognized as a NATO Advanced Study Institute (ASI).