This book constitutes the refereed proceedings of the 7th European Conference on Wireless Sensor Networks, EWSN 2010, held in Coimbra, Portugal, in Februar 2010. The 21 revised full papers presented were carefully reviewed and selected from 109 submissions. Topics of interest include hardware design and implementation, operating systems and software, 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. The papers are organized in topical sections on localization, synchronization and compression, networking, new directions, programming and architecture, as well as on link reliability.