Mobile ad hoc networks (MANETs) are self-organizing, infrastructureless networks that provide flexibility and convenience in setting up a dynamic network. Since the 1970's, MANETs have attracted a great deal of research aimed at improving their basic performance. However, with the development of real-time applications, incorporating Quality of Service (QoS) into the network architecture becomes essential. Supporting QoS in MANETs necessitates more harmonious collaboration among all network layers, requiring a design that supports cross-layer interactions rather than a traditional independent layered network architecture. The work described in this book enables this goal by proposing a general architecture that supports cross-layer interactions, as well as by designing protocols at several layers of the stack that can exploit this cross-layer information to improve the QoS performance. This book is addressed to professionals in wireless networks, especially those interested in protocol design for supporting QoS in MANETs.