Americans are living longer and more fulfilling lives. They desire to live as independently as possible, but independent lifestyles come with risks, such as debilitating falls that limit mobility. To address these issues, researchers are developing "smart home" technologies to enhance residents' safety and monitor health conditions using sensors and other devices. In particular, the continuous assessment of physical function is a key indicator of initial decline in health and functional ability. Identifying and assessing problems while they are still small can provide a window of opportunity for interventions that will alleviate the problem areas before they become catastrophic.