This chapter proposes a smartphone-based system for both indoor and outdoor monitoring of people with dementia. The whole system comprises wandering detection, safety-zone monitoring, fall detection, communication services, alert notifications, and emergency medical services. To effectively track the elderly, the proposed system uses a smartphone camera to take real-time pictures along the user's path as he or she moves about. Those photos, accompanied with time and GPS signals, are delivered to and stored on the Cloud system. When necessary, family caregivers can download those data to quickly find a way to help the elderly individual. Additionally, this study uses tri-axial accelerometers to examine falls. To assure individuals' data is safeguarded appropriately, an RSA method has been adopted by the system to encrypt stored data. This reliable and minimally intrusive system provides people with dementia with an opportunity to maintain their social networks and to improve their quality of lives.