Multicast technology is highly efficient for the large scale multimedia content service delivery. Its efficiency is maximized when all the service recipients have identical needs. In reality however, the end users may have a heterogeneous set of requirements for different service levels as well as different service components, depending on their system and network capabilities. We propose the notion of Service Adaptive Multicast (SAM) that balances the tradeoffs between providing individualized service to each client and maintaining an efficient overlay multicast tree structure. The novel aspects of our approach are (a) the ability to augment and transform existing paths into service paths with the desired attributes; and (b) integration of two tree maintenance processes: a receiver-initiated just-in-time adaptation of the multicast service tree driven by application/user perceived QoS, and a demand-driven tree maintenance process geared towards long-term tree quality. We demonstrate the performance of our approach using simulations of large client population.