This chapter outlines an evolutionary path of various 802.11 networks. It draws on guidelines for system planners to design and deploy indoor Wireless local area network (WLAN) systems. The chapter discusses the issues in the deployment of WLANs in single- and multifloor office buildings. It provides various approaches in achieving high-performance in WLANs using cross-layer design. The chapter presents a set of guidelines for planning and deploying indoor WLANs. Both 802.11g and 802.11a offer moderate system performance and are commonly used in homes, offices, and hotspots for Internet access. Deploying an enterprise WLAN is a new challenge even for experienced system planners. When planning for deployment of an infrastructure WLAN in an obstructed office space, system planners need to determine the optimum number and locations of access points to achieve the desired performance and coverage. When planning a WLAN in a typical suburban residential house, system planners need to quantify the effect of line-of-sight blockage by walls and furniture on system performance.