This paper presents a new approach that exploits Semantic Web standards to provide a reusable middleware support for flexible event representation, query and reasoning, and standardized schemes for automated intervention triggering and activity planning to handle agitation detected in persons with dementia. The proposed context model enables the development of sophisticated systems that facilitates caregiving and clinical assessment of dementia patients in a context enlightened fashion. In particular, we describe the use of the Web Ontology Language (OWL) to model agitation quantification using Scale to Assess Observed Agitation in Persons with Dementia of the Alzheimer Type (SOAPD), intervention and social contexts to build an integrated monitoring and intervention system that exceeds the current state-ofthe- art in robustness, intelligence and scalability.