This study investigated the impact of renovation and redesign of a university preschool’s outdoor space on children’s sedentary behavior, light activity, and moderate-to-vigorous-physical-activity (MVPA) during unstructured recess. Physical activity was measured by accelerometry and direct observation in two independent samples of 50 (baseline) and 57 (postintervention) children (M age=4.4 yrs ± 0.5). Controlling for gender, age, BMI and recess length, observational data, but not accelerometry, revealed a significant decrease in intervals spent sedentary (-26.5%) and increases in light physical activity (+11.6%) and MVPA (+14.9%). Higher levels of MVPA were associated with specific environmental changes (new looping cycle path, OR = 2.18; increased playground open space, OR = 7.62; and new grass hill, OR = 3.27). Decreased sedentary behavior and increased light activity and MVPA may be realized with environmental changes that promote continuous and novel movement experiences in more expansive spaces.