Context awareness is a key issue for applications within heterogeneous and networked environments. In terms of efficiency and reusability, such applications need to be separated from the problems of context gathering and modeling, but should instead profit from and contribute to cross-application context information. For this purpose, an ontology-based, cross-application context modeling and management service is required to provide appropriate support for the variety of conceivable application scenarios. Although there have been numerous approaches dealing with application-independent context management, none of them sufficiently supports the vision of cross-application context handling. Therefore, this paper presents CroCo, an ontology-based context management service that allows for cross-application context gathering, modeling, and provision. The authors successfully verified and tested the application independency and practicability of this novel concept within three different projects with disparate application scenarios.