An evaluation was conducted of the effectiveness of a six-month moderate-intensity physical activity intervention for increasing total daily energy expenditure of sedentary African-American women who were between the ages of 50 and 70 years. The goal of the intervention was to increase total daily energy expenditure by 150 kilocalories per day and time spent in moderate-intensity physical activity by 30 minutes per day. Effects of increased physical activity on selected cardiovascular risk factors (e.g., peak oxygen uptake, blood pressure, HDL cholesterol, serum insulin and plasma glucose) were also determined. Six churches were randomized into intensive or minimal intervention status, and 33 women per church were recruited, for a total of 100 women in each condition. The physical activity intervention consisted of twice-weekly aerobics classes conducted at the churches and additional group-and home-based programming. Volunteer lay leaders were trained as neighborhood exercise specialists to supplement certified aerobics instructors in conducting the intervention.