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 support: Ministerio de Educaci' on y Ciencia of the Sp- ish Government, AGAUR of the Generalitat de Catalunya, Universitat de Barcelona, and the Centre Especial de Recerca (CER) F' ?sica de Sistemes Complexos. As in former editions of the Conference, the city of Sitges allowed us to use the beautiful Palau Maricel as the lecture hall. We thank them for their kind hospitality. We are also very grateful to all those who collaborated in organizing the event: M. Naspreda, A. P' erez-Madrid, R. Pastor-Satorras, and S. Zapperi. Finally, we wish to express our gratitude to all the speakers and parti- pants in the Conference, who contributed with high scienti?c level presen- tions, and created a very pleasant atmosphere.

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 support: Ministerio de Educaci' on y Ciencia of the Sp- ish Government, AGAUR of the Generalitat de Catalunya, Universitat de Barcelona, and the Centre Especial de Recerca (CER) F' ?sica de Sistemes Complexos. As in former editions of the Conference, the city of Sitges allowed us to use the beautiful Palau Maricel as the lecture hall. We thank them for their kind hospitality. We are also very grateful to all those who collaborated in organizing the event: M. Naspreda, A. P' erez-Madrid, R. Pastor-Satorras, and S. Zapperi. Finally, we wish to express our gratitude to all the speakers and parti- pants in the Conference, who contributed with high scienti?c level presen- tions, and created a very pleasant atmosphere.

Clodomir Santos de Morais is to organizational and entrepreneurial literacy what his Brazilian confrere, Paulo Freire, is to ordinary literacy. This book introduces for the first time in English the experiences of grassroots development workers who have applied his ideas of the Organization Workshop (OW) and capacitation in highly diverse social settings. One of the most exciting aspects of de Morais's methods of working with the most marginalized sectors of society is their relevance not just to Third World countries, but also to Eastern Europe's economies in transition and the most deprived areas of the industrialized countries. This highly distinctive grassroots development approach to empowering socially excluded strata in economic and organizational terms holds out the prospect of becoming a very important factor in the struggle against poverty.