Purpose. To evaluate the effectiveness of Preventing Obesity by Design (POD), a childcare center outdoor renovation intervention. Design. Pre-post intervention evaluation. Setting. North Carolina licensed childcare centers (N = 27). Subjects. Preschool children. Intervention. Outdoor renovation, teacher training. Measures. Behavior mapping, Preschool Outdoor Environment Measurement Scale (POEMS), center director interview. Analysis. Descriptive statistics, ordinary least squares and logistic regressions calculated to assess levels of association between environmental change, children's physical activity (PA), social behaviors, and environmental quality. Qualitative interview data analyzed to help understand intervention impact. Results. Behavior mapping showed that site layout attributes, such as the form (i.e., "single loop" and "double loop") of pathways (functioning as circulation routes and wheeled toy settings), are associated with higher levels of PA. Teacher interaction was associated with decreased children's PA. Absence of teacher or lack of child/child interaction was associated with increased PA. POEMS assessment of environmental quality was higher after renovation. POEMS domains (Physical Space and Teacher/Caregiver Roles) were positively associated with PA. After renovation, 68% of center directors reported positive changes in children's behavior and 40% mentioned edible plant installations as greatest success. Conclusion. Built environment renovation of childcare center outdoors, including looped pathways installation, coupled with teacher training, may support increased PA. Renovation, including food gardens, may be a key to success for preschool health promotion and support change in childcare policy. (author abstract)