Security is a critical issue in wireless local area networks (WLANs) for many individuals and organizations worldwide, and is one of the main barriers to its adoption in organizations. A good understanding of both the WLAN technology and security issues is required to assist optimum planning and implementation of such systems. In the investigation, a warwalking (field trials) approach is considered. It is observed that the use of WLANs in Auckland city has increased by 114.41% since 2004. It is also observed that about 74.31% of all WLANs detected on 26th June 2007 utilized encryption technology while the remaining 25.69% did not use encryption at all. This shows that overall 86.56% increase in the use of encryption compared to the data collected in 2004. There are various security measures that businesses can adopt to ensure the security of their wireless networks. The techniques that will be discussed further are the enabling of WEP or WPA, MAC address filtering, virtual private network, intrusion detection system, running network simulation, and performing security risk assessment.