Mobile networks and particularly UMTS bring to the service provision context a new concept, known as Virtual Home Environment (VHE), that advocates services totally independent of network and terminal technologies. The VHE concept gains particular importance in the provision of next generation services, characterized not only by location based features, but also by context-aware features, multimedia contents and user mobility. The work presented here moves in two main directions. Firstly, the definition of an architectural framework for the materialization of the VHE, decoupling all the aspects that are VHE specific from the basic service functionality, in order to facilitate the service creation process. Secondly, a proposal to solve the problem of the adaptation of multimedia services in mobile contexts. The book combines context-awareness techniques with user interface modeling to dynamically adapt telecommunications services to user resources, in terms of terminal and network conditions. The solution is mainly characterized by the approach used for resolving the existing dependencies among user interface variables, which is based on the constraints theory.