Due to the development of computer hardware technology, the use of portable computers has become more popular. Research workers have become more and more interested in wireless mobility related to these new hardware technologies. Much work focusing on Mobile IP has been done. However, there exist some issues such as "Triangle Routing" in Mobile IP. It has been found that SIP-based (Session Initiation Protocol) mobility has advantages that can be used to avoid the issues in Mobile IP. Based on this idea, this thesis first introduces the previous work related to mobility as well as mobility with multicast, and presents some issues that exist in IP mobility with multicast. Then we provide an approach called "Multicast Mobility Support in Session Layer Using SIP", which is independent of the IP layer and automatically avoids the issues in IP layer. The structure of the SIP mobility with multicast is presented and a proposal to extend SIP functions for supporting SIP multicast mobility is provided. Based on the system model built by using SDL (ITU Specification and Description Language), we used ObjectGeode tool set to simulate the proposed idea presented in this thesis. This work may be helpful to shift the concept of multicasting and mobility from IP layer to session and application layers for real time multimedia.