This volume contains the proceedingsof EWSN 2009, the 6th European Conf- ence on Wireless Sensor Networks. The conference took place in Cork, Ireland during February11-13,2009. The aim ofthe conferencewasto discussthe latest research results and developments in the ?eld of wireless sensor networks. EWSN received a total of 145 full paper submissions of which 23 were - lectedfor publicationandpresentation, yielding anacceptancerateofjust under 16%. Paper submissions were received from 36 di?erent countries in all parts of the world. EWSN adopted a double-blind review process, where the identities of the paper authors were also withheld from the reviewers. The selection process involved well over 400 reviews with all papers being evaluated by at least three independent reviewers. In addition, the reviews were discussed by the Technical Program Committee after collecting all reviews and prior to making ?nal - cisions. The ?nal program covered a wide range of topics which were grouped into six sessions: performance and quality of service, routing, coordination and synchronization, data collection, security, evaluation and management. It - cluded theoretical and analytical approaches, together with empirical research and protocol/system design and implementation. The conference included a demo and poster session, co-chairedby Dirk Pesch andSajalDas, forwhichseparateproceedingsareavaila