Purpose. To evaluate the ability of the SenseWear® Armband to assess a change in energy expenditure in children while sitting and standing at a desk in a controlled environment. Methods. This study was performed with 21 children ages 7-10. The children wore the SenseWear Armband while sitting at a traditional desk and then while standing at a height-adjusted standing desk with a swinging footrest for 30 minutes each. The second 10-minute period of data for each activity was analyzed for significant differences in the average energy expenditure between the two activities, and, therefore, the devices ability to detect these differences. Results. Complete data were collected for all 21 subjects. The overall mean energy expenditure for sitting was 0.63 kcal, ranging from 0.39-1.08. The overall mean energy expenditure for standing was 0.71 kcal, ranging from 0.40-1.10. The average of the differences in energy expenditure over 10 minutes of data was significantly different from zero when subjects were standing (p < 0.0001). The standard deviation of the differences of the mean energy expenditure between sitting and standing was 0.06 and the mean was 0.09. Conclusions. The SenseWear Armband is sensitive enough to detect a change in energy expenditure in children 7-10 years of age while sitting and standing. As expected, when subjects were standing, the average energy expenditure increased. Use of the SenseWear Armband on children, and to assess slight changes in energy expenditure in general, appears to be practical and sensitive.