This paper describes a method for designing, implementing, and evaluating a work-site physical activity campaign aimed at employees who are currently sedentary in their leisure time. Inactivity is a major but modifiable risk factor for coronary heart disease. Increasing the activity levels of underactive adults would have a positive impact on public health. Worksites provide an effective channel for reaching a large proportion of the sedentary population, as most adults spend approximately 8 hours of their day at their place of employment. By targeting the least active segment of the work force, the greatest benefits will be realized, not only by the individuals but by their employers as well. Worksites that effectively promote physical activity can expect to see increased productivity and employee morale, and decreased absenteeism and health insurance costs. Step-by-step procedures and important factors are outlined including: (1) conducting a needs assessment; (2) using Baranowski's Syntheoretical Model (Baranowski, 1992) to develop the theoretical framework for the campaign; (3) sample activities, such as walking, beginner aerobics, backyard gardens, lunch-time sports, small behavioral changes, and supervisory support; (4) strategies for promoting the campaign among employees; (5) achieving sustainability for the campaign; (6) evaluation, including process evaluation, income measures, and outcome measures; and (7) practical considerations for the success of the campaign. (Contains 11 references.) (ND)