The emergence of quad-play services (i.e., voice, video, data, and mobility) leads to a stronger integration of optical and wireless networks. The resultant bimodal fiber-wireless (FiWi) access networks aim at providing wired and wireless services over the same infrastructure simultaneously, thus potentially leading to major cost savings. Ethernet passive optical network (EPON) is a promising technology to increase the per-user bit rate for bandwidth hungry-applications in fiber-to- the-home (FTTH) networks. Similarly, next-generation WLAN supports users with mobility in wireless networks. Until now, however, security has been mostly discussed separately either in wireless or optical networks. No profound research activity has been conducted on security in integrated FiWi networks so far. To our knowledge, this is the first research work on security in emerging hybrid FiWi broadband access networks. This book focuses on security issues like mutual authentication, data confidentiality, integrity, and access control in hybrid FiWi broadband access networks. Toward this end, a security policy based on IPSec is developed by adapting extensible authentication protocol (EAP).