Nearly two-thirds of all babies born in Los Angeles County are enrolled in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC), which serves pregnant, breastfeeding and postpartum women, and children up to 5 years old from low-income families. Public Health Foundation Enterprises (PHFE)-WIC, the largest local agency WIC program in the country, with support from First 5 LA, maintains a large geocoded database of all WIC participants in Los Angeles County. This webinar will discuss collaborations between the UCLA Fielding School of Public Health and PHFE-WIC, with a focus on the NIH-funded Early Childhood Obesity Systems Science Study, to evaluate the effectiveness of programs and policies on childhood obesity using a systems science approach.