Context-awareness is a key issue for future applications within heterogeneous and networked environments. In terms of efficiency and reusability, such applications should 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 needed 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, we present CROCO, an ontology-based context management service that allows for cross-application context gathering, modeling, and provision. We verified and tested the practicability of our concept within two different projects with disparate application scenarios.