Multicasting is a key technology for both users and service providers as it enables important bandwidth savings, and thus lower costs, for content distribution and group communication. The current network level multicast solutions have several weaknesses. These issues are partly related to a problem embedded in the use of the IP addresses themselves. Currently an IP address is both an identifier of who I am and where I am. The Host Identity concept tries to solve this problem by introducing a new, unique identifier, the Host Identity Tag. This concept was used, up until now, mainly for unicast communications. In this paper we propose thus the Host Identity Specific Multicast (HISM) model; we present the architectural elements of the model, and show how it handles access control, mobility, and how it provides native network layer multicast support in mixed, IPv4-IPv6 environments.