WithgreatpleasurewewelcomedtheattendeestoEWSN2004, the1stEuropean Workshop on Wireless Sensor Networks, held in the exciting and lively city of Berlin. Wireless sensor networks are a key technology for new ways of interaction betweencomputersandthephysicalenvironmentwhichsurroundsus.Compared to traditional networking technologies, wireless sensor networks are faced with a rather unique mix of challenges: scalability, energy e?ciency, self-con?guration, constrainedcomputationandmemoryresourcesinindividualnodes, data-cent- city, and interaction with the physical environment, to name but a few. The goal of this workshop is to create a forum for presenting new results in the ?ourishing ?eld of wireless sensor networks. By bringing together academia and industry we hope to stimulate new opportunities for collaborations. In compiling the scienti?c program we have been quite selective. Thanks to the e?orts of 90 reviewers who delivered 252 reviews for the 76 papers originally submitted from all over the world, a strong selection of the 24 best contributions was made possible. The Technical Program Committee created an outstanding program covering the broad scope of this highly interdisciplinary ?eld: from distributed signal processing through networking and middleware issues to - plication experience. Running such a workshop requires dedication and much work from many people. We want to thank in particular Petra Hutt, Irene Ostertag and Heike Klemz for their valuable and esteemed help in the local organization of this workshop. We hope that you enjoy this volume, and if you were lucky enough to - tend we hope that you enjoyed the discussions with colleagues working in this fascinating are