Decision makers must know if their cyber assets are ready to execute critical missions and business processes. Net-work operators need to know who relies on a failed network asset (e.g. IP address, network service, application) and what critical operations are impacted. This requires a mapping between net-work assets and the critical operations that depend on them, currently a manual and tedious task. In addition, because of the dynamic nature of networks and missions, manual mappings of network assets to operational missions rapidly become outdated. This paper describes one approach to modeling the complex relationships between cyber assets and the missions and users that depend on them, using an ontology developed in conjunction with practitioners and cyber mission assurance researchers. We de-scribe the “Camus” (cyber assets, missions and users) proof of concept, which uses this ontology and automatically populates that model from data already on the network. We discuss the technical approach and provide examples of query results returned by the model. We conclude by describing ongoing work to enhance this proof of concept and its potential applicability to support mission assurance and mission impact solutions.