This study examined the effect of including workplace physical activity in calculating the proportion of adults meeting Centers for Disease Control (CDC) guidelines for physical activity. Data on leisure-time and workplace activity were collected from 1,090 Black and White adults in St. Louis, MO. A series of assumptions were used to equate workplace and leisure-time physical activity. Depending on the assumptions used, we found an absolute increase of 5.5% to 8.4% of individuals meeting the moderate activity guidelines and an absolute increase of 1.5% to 1.7% for the vigorous activity guidelines. Men were significantly more likely than women to be reclassified as meeting the vigorous standard ([chi[superscript 2]] = 8.016, p less than 0.005) when workplace activity was included. The existing policy of excluding workplace activity in the definition of physical activity has led to an underestimate of adults meeting the CDC guidelines, especially among men. (Contains 4 tables.)