Exercise professionals have little information concerning expected levels of exercise for new participants. This study examined the frequency of exercise of 949 employees during their first 6 months of membership in a work-site health promotion facility, using automated check-in data. Overall, the frequency of exercise declined, the proportion of frequent exercisers declined, and the proportion of employees who dropped out increased. Men exercised more frequently and were less likely to drop out than were women (P < .01). Younger employees exercised more frequently than did older employees. Employees in the middle salary level exercised more frequently than did employees in the lower or upper levels (P < .01). The employee groups that started out with a lower frequency of exercise remained at a lower frequency throughout the 6 months. By their 6th month, women were 50% more likely to drop out and 50% less likely to exercise regularly than were men. These figures provide a basis for comparison with other programs to document expected exercise behavior.