Capturing information about employees can give organizations insight into underlying knowledge processes. Analyzing email communications, for example, can produce an informal structure that's flexible and that organizations can recalculate regularly to capture information flow among employees. The structure could also help institutions to both identify collaboration patterns and predict changes in those patterns. Using semantic technologies in various domains, researchers have developed domain-specific ontologies to capture knowledge and enable reasoning. Organizations can support such knowledge management by capturing knowledge of their own people and their communication records, including email exchanges. The proposed approach analyzes an internal social network and uses the resulting information to produce an informal organizational structure. The authors evaluated their approach using a mid-size organization's actual data and compared the informal structure they obtained with the formal organizational structure. As the results show, the approach proved useful for modeling social structures based on real-world communication records.