The eHealthMonitor project provides a platform that generates a Personal eHealth Knowledge Space (PeKS) as an aggregation of all knowledge sources (e.g., EHR and PHR) relevant for the provision of individualized personal eHealth services. This is realised by integrating service-oriented architecture, knowledge engineering, multiagent systems, and wearable/portable devices technologies. Innovations in eHealthMonitor are: (1) an adaptive, sustainable platform architecture for individualized personal electronic healthcare services; (2) reasoning, model evolution, and model summarization methods based on semantic models with different degrees of granularity, specificity, and different types of heterogeneity (syntactic, lexical, semantic); (3) distributed, adaptive knowledge sharing coordination methods which consider privacy protection requirements; and (4) personal eHealth services that support cooperation and decision making of the involved participants (patients, clinicians, social services): medical decision support services, personal information services, environmental and lifestyle risk factor monitoring services, and physiological and bio-chemical data monitoring services.The eHealthMonitor platform and health services are evaluated in three case studies: Deployment of the platform in two hospital scenarios built around two of the most relevant issues in the current EU eHealth environment – (1) dementia and (2) cardiovascular diseases – involving patients and medical professionals. (3) Deployment of the eHealthMonitor platform as part of prevention strategies where an insurance company provides its clients (patients and non-patients) access to the eHealthMonitor services in order to lower the risk of potential diseases.The impact is ensured through an active open source (OS) strategy which bases all basic software components on existing OS software and releases developed eHealth reference processes and guidelines as open models through Open Model Initiative.