The book constitutes the refereed proceedings of the Second International Conference on Distributed Computing in Sensor Systems, DCOSS 2006, held in San Francisco, California, USA in June 2006.The 33 revised full papers presented were carefully reviewed and selected from 87 submissions. The papers focus on distributed computing issues in large-scale networked sensor systems, including systematic design techniques and tools; they cover topics such as distributed algorithms and applications, programming support and middleware, data aggregation and dissemination, security, information fusion, lifetime maximization, and localization.