This volume gathers a number of selected contributions from the XIX Sitges Conference on Jamming, Yielding, and Irreversible Deformation in C- densed Matter, held at Sitges (Barcelona, Spain) from 14 18 June, 2004. The contributions collected in this volume provide a general overview of the state of the art, and of the recent developments, in the ?elds of material yield and irreversible deformation in di?erent physical systems, which are of great interest within the realm of Condensed Matter Physics. The Conference was sponsored by several institutions that generously provided ?nancial...