This monograph presents the outcome of a GI-Dagstuhl Seminar held in Dagstuhl Castle in November 2005. It gives a first overview of algorithmic results on wireless ad hoc and sensor networks. Many chapters deal with distributed algorithms. Importance is attached to topics that combine both interesting aspects of wireless networks and attractive algorithmic methods. Each chapter provides a survey of some part of the field, while selected results are described in more detail.