In adaptive learning environments, this exchange of online presence data cannot be considered isolated from the overall learning context. However, there is yet no systematic solution to exchanging and integrating online presence data from diverse instant messaging and social networking applications. To address this issue, we propose an ontology-based approach to sharing online presence data in adaptive learning environments through the use of the Online Presence Ontology. This ontology is integrated into the Learning Object Context Ontology framework, which allows for capturing and unambiguous representation of all relevant data about students online presence, their mutual interactions, as well as their interactions with learning resources. On top of this ontology framework, we have developed innovative, contextaware learning services presented in this paper. The use of these services is demonstrated in a learning environment for studying software patterns.