ThisvolumecontainstheproceedingsofEWSN2008, the?fthEuropeanConf- ence on Wireless Sensor Networks, held in Bologna, Italy, during January 30-31 and February 1, 2008. Its scope was the creation of a forum where researchers with di?erent ex- rience and background could discuss cross-layer approaches, novel solutions for speci?c problems and envisage the future development of wireless sensor n- works (WSNs). Out of the 110 papers that were submitted, 23 were selected after a doub- blind peer-review process, leading to an acceptance rate of 21%. Six among the accepted papers included authors from North America, three from Asia, all others from Europe with the exception of one from Australia, and one from Brazil: the conference brought together researchers from almost all corners of the world! Demonstration and poster papers were also presented at the conference, of which separate proceedings were produced, under the supervision of the other TPC Co-chair, Zach Shelby from Sensinode ltd, who managed the reviews of these papers. The rangeoftopicscoveredby this conference, including communicationp- tocols, information processing, middleware, operating systems, hardware and ?eld tests, is very wide. This made the vision of a coherent ?nal technical p- gramme more di?cult, as few papers cover each of the various topics. But what made such a process even more challenging, is the intrinsic nature of WSNs, which is cross-layer and requires the joint consideration of many aspects when measuring or predicting the performance of a given algorithm, protocol, or te- nical solution.