Physical activity (PA) at a young age is an important health behavior to prevent childhood obesity and establish healthy PA habits. Because the majority of preschool-age children attend child-care centers, child-care environment can play an important role in promoting PA among this population. This study examined environmental factors associated with children’s moderate-to-vigorous intensity physical activity (MVPA) during indoor and outdoor PA sessions at urban child-care centers. Investigators observed daily activity schedules, recreational space, and play equipment at 16 Chicago child-care centers in winter and spring of 2011, and measured child PA using ActiGraph accelerometers for preschoolers ages 3 to 5 years. Statistical analyses were conducted to predict MVPA time and inactivity time during indoor and outdoor PA sessions. More indoor play equipment, structured PA sessions, and spring season were associated with more MVPA during indoor PA sessions. Presence of an outdoor playground and spring season were associated with more MVPA during outdoor PA sessions. These findings support previous studies that indicate the positive impact of access to PA space and equipment on child engagement in PA, and suggest the need for more detailed strategies in scheduling structured PA sessions.