Tai Chi is an ancient Chinese form of calisthenics that promotes relaxation and decreases feelings of stress and as such, it may be a useful intervention for socially isolated, stressed older adults. However, its effects on stress responses are unknown. Tai Chi Chih (TCC) is a simplified, manualized, readily exportable form of Tai Chi particularly well-suited for older adults. This proposed study will test the effects of a TCC intervention with socially isolated older adults on loneliness, stress and health outcomes, including inflammatory assessment. Tai Chi-naïve participants who perceive themselves as socially isolated, as measured by the UCLA Loneliness Scale will be randomized to receive either Tai Chi or education control for a 12-week period. Subjects will undergo pre- and post-intervention stress assessment, including exposure to a psychological stress task, to assess whether Tai Chi affects how subjects physiologically and psychologically respond to stress.