This volume contains the proceedings of the Third International Conference on Network Control and Engineering for Quality of Service, Security and Mobility (Net-Con'2004), celebrated in Palma de Mallorca (Illes Balears, Spain) during November 2-5, 2004. This IFIP TC6 Conference was organized by the Universitat de les Illes Balears and sponsored by the following Working Groups: WG6.2 (Network and Internetwork Architectures), WG6.6 (Management of Networks and Distributed Systems), WG6.7 (Smart Networks) and WG6.8 (Mobile and Wireless Communications). The rapid evolution of the networking...