It is our great pleasure to present the proceedings of the European Conference on Wireless Sensor Networks 2010 (EWSN 2010). As the field of wireless sensor networks matures, new design concepts, experim- tal and theoretical findings, and applications have continued to emerge at a rapid pace. As one of the leading international conferences in this area, EWSN has played a s- stantial role in the dissemination of innovative research ideas from researchers all over the globe. EWSN 2010 was organized by the University of Coimbra, Portugal, during February 17-19, 2010 and it was the seventh meeting in this series. Previous events were held in Berlin (Germany) in 2004, Istanbul (Turkey) in 2005, Zurich (Switz- land) in 2006, Delft (The Netherlands) in 2007, and Cork (Ireland) in 2009. A high-quality selection of papers made up EWSN 2010. Based on the reviews and the recommendations from the four live TPC discussions, we selected a total of 21 papers from 109 submissions (19.26% acceptance rate) for EWSN 2010. Topics of interest included hardware design and implementation, operating systems and so- ware, middleware and macroprogramming, communication and network protocols, information and signal processing, fundamental theoretical limits and algorithms, prototypes, field experiments, testbeds, novel applications, including urban sensing, security and fault-tolerance. Putting together EWSN 2010 was a team effort. We would like to thank the P- gram Committee members, the reviewers, our sponsors, all authors, and the Organ- ing Committee for their respective contributions.