Herein, we present UbiCare, an AAL system based on a cost-effective WSN installation. The key objective of UbiCare is to support the safe independent living of elderly living in their home environment; also to mitigate the stress caused to elderly individuals living in non-supervised areas. The main function of the proposed system is to record the daily activity of the elderly (e.g., presence/movement in specific home areas, sleeping, seating, usage of electrical appliances or sanitary facilities) and environmental monitoring (temperature, humidity, light intensity). Prospectively, significant deviations from the “normal” activity pattern (for instance, prolonged immobility on the bed or detection of prolonged presence at home without food consumption) could be interpreted as evidence of incapacitation or reason to issue alarm. UbiCare may also issue alarms to authorized caregivers (e.g., relatives and/or doctors) in the event of fall detection, thereby improving the achievable level of security and ensuring immediate nursing treatment of such incidents; alarms may be implemented by a variety of methods, e.g., automated sending of SMS, emails or voice calls. Activity information is recorded in a web database and visualized in an intelligible form via a web interface.