It has been suggested that physical activity levels vary by season. However, little is known about how the physical activity levels of children vary by season, specifically when objectively measured by pedometry. The purpose of this study was to use pedometers to measure and compare children's physical activity levels during the winter and spring. Participants were 217 elementary school children (120 girls) living in the southern United States with a mean age of 9.2 ± 1.46 years. Physical activity was assessed in daily step counts over 24-hrs for four consecutive days using the MLS-2505 pedometer (Plainfield, IL). During the winter, girls accumulated 8011 ± 2563 steps and boys 8952 ± 2758 steps per day. During the spring, girls accumulated 9881 ± 3645 while boys accumulated 11024 ± 4612 steps, respectively. Significant differences in total physical activity by season were found (t(216) = 7.17, p < .001). Specifically, physical activity was significantly lower in winter than in spring. Although there were significant gender differences in physical activity during both winter and spring (ps < .01), the variability in physical activity was greater during the spring assessment. These data highlight the importance of promoting physical activity during the winter months when both boys and girls are significantly less active. Further, this study indicates that children in this study, even during the spring, are substantially less active than previously reported levels for similarly aged children. Keyword(s): measurement/evaluation, physical activity, research