While the medical care encounter is considered an ideal situation in which patients are encouraged to increase their physical activity levels, very little research has been conducted in this setting. In fact, with the exception of the physical activity components of cardiac rehabilitation programs, few formal physical activity programs are available in medical care settings. Although the workplace is currently the focus of the greatest interest by those persons who implement physical activity programs, there is little precision in defining what constitutes a worksite physical activity program. A number of researchers and authors, using program experience rather than empirical findings, have described what they believe to be the important components of successful worksites health promotion and physical education programs. The greatest variety of physical activity programs are found in community settings. They are offered by a number of nonprofit private organizations, nonprofit public agencies, and for-profit organizations. While relatively little research has been done concerning changes in the community environment, it is clear that such changes can effect community participation. Community campaigns to increase physical activity have been studied, and it appears that they clearly affect residents' interest and awareness in physical activity, but they do not have a major effect on behavioral changes in the short term. It appears that a major opportunity to influence favorable physical activity in the United States is being missed in schools. A large majority of students are enrolled in physical education classes, but the classes appear to have little effect on the current physical fitness levels of children and, furthermore, have little impact on developing life-long physical activity skills.