Context-aware service platforms need to establish and manage trust relationships for users to know if the user's privacy policies are being enforced and for service providers to control access to their services. Current trust solutions are not suitable for this because they do not address in an integrated manner trust issues related to identity provisioning, privacy enforcement and context information trustworthiness. In addition, due to their hierarchical and centralized design, current trust management solutions do not scale well in the ad-hoc pervasive environments in which context-aware platforms are typically deployed. In this paper we propose context-aware trust domains as a management solution for context-aware service platforms.