It is our great pleasure to welcome you to ACM WiSec 2010, the Third ACM Conference on Wireless Network Security, at Stevens Institute of Technology, Hoboken, USA. This conference grew out of three similarly-themed workshops that had been running for several years: ESAS (European Workshop on Security of Ad Hoc and Sensor Networks), SASN (ACM Workshop on Security of Ad Hoc and Sensor Networks), and WiSe (ACM Workshop on Wireless Security). The merger consolidated the three workshops into one annual event that would attract the most significant research results in wireless security from around the world. Keeping this in mind led to a very strict and competitive selection process among the 99 submissions. Of these, nine outstanding works were chosen for presentation as full papers, for an acceptance rate of 9%. Twelve submissions were accepted for revision and presentation as short papers, for an overall conference acceptance rate of 21%. The highly selective program of refereed papers is complemented by keynote presentations from two outstanding pioneers, Andrew Odlyzko and Philip Zimmermann. For the first time, the program also includes two sessions for poster presentations and practical demos. We trust that WiSec 2010 will offer everyone, whether presenters or attendees, a great opportunity to share their perspectives and experiences with their peers. Enjoy the event and the interaction! For those reading the proceedings after the fact, we hope that you will find them a valuable reference to the latest and most significant developments in our field.