The convergence of different classes of traffic with different priorities over the wire- less network has become a reality. To insure that the users of key applications such as VoIP are satisfied with the service they receive, one must insure that the QoS criteria for these applications, such as delay, jitter or packet loss, are met. This in turn means that some form of Connection Admission Control must be used. In this paper, we show how the notion of Effective bandwidth that had been previously used in wired systems can be used for CAC in WLAN IEEE 802.11b and 802.11g networks. Effective Bandwidth simplifies connection admission since a new application can be accepted on a link whenever its effective bandwidth is lower than the bandwidth still available on the link. The paper presents empirical results obtained by extensive simulations showing that the admission region is nearly linear so that it is possible to design an effective linear CAC policy based solely on the effective bandwidth of a connection. We also propose a more practical method that relates to per packet effective bandwidth.