My greatest motivation for writing this book remains how we can ameliorate the functionalities of some part(s) of Network Access Control (NAC) to improve IT security performance. Interestingly, this study will look deeply into NAC as to knowing its components, how it works in large networks like mine, its benefits, why it is so important to our era and ways to optimize its functions. Traditionally security programs acting separately are no longer adequate to tackle today¿s network security threats. It calls for a unified system with constant communication and reporting software such as the intrusion detection and prevention technologies (IDS/IPS), firewalls, antivirus and SIEM to secure today¿s network. It calls for more surveillance on applications, web portals and operating systems now residing in both public, private or hybrid clouds. Throughout the following chapters, we will look deeply into NAC by analyzing its role in the company that I found myself. We will discover how NAC works, its constraints and limitation and will propose better ways to optimize its functionalities so as to achieve the next generation security that we need.