This review offers an update of the psychological effects of Tai Chi Chuan (TC) among different populations. A computerized literature research from 1990 to June 2006 was carried out. Studies were selected when they assessed the mental and psychological effects of TC practice among various populations. Data from 14 studies for a total of 829 subjects, age range from 12 to 96 years, were considered here. There were eight randomized controlled trials and six quasi-experimental or case control studies in this review. The intensity of TC varied from 30 min twice a week over a 5-week period to 1 h every day over an 8-week period. TC was characterized as a kind of light-to-moderate exercise and was found to enhance overall psychological well-being and to improve self-efficacy and mood. TC benefits appeared to be more tangible for adults and healthy older adults or those becoming frail. However, TC did not appear to be more efficient than exercises of the same intensity. Extensive and qualitative studies are needed to quantify the effects of the volume of practice, expert modeling, gender differences, and the age-related learning process on efficacy cognitions and mood in clinical and nonclinical contexts.