Childhood obesity is associated with negative health consequences in childhood (1) that continue into adulthood (2), putting adults at risk for type 2 diabetes, cardiovascular disease, and certain cancers (1). Obesity disproportionately affects children from low-income families (3). Through a collaboration with the United States Department of Agriculture (USDA), CDC has begun to use data from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) Participants and Program Characteristics (WIC PC) to replace the Pediatric Nutrition Surveillance System (PedNSS) (4,5) for obesity surveillance among young children from low-income families. CDC examined trends in obesity prevalence during 2000-2014 among WIC participants aged 2-4 years using WIC PC data. Overall obesity prevalence increased from 14.0% in 2000 to 15.5% in 2004 and 15.9% in 2010, and then decreased to 14.5% in 2014. During 2010-2014, the prevalence of obesity decreased significantly overall, among non-Hispanic whites, non-Hispanic blacks, Hispanics, American Indian/Alaska Natives and Asians/Pacific Islanders, and among 34 (61%) of the 56 WIC state agencies in states, the District of Columbia, and U.S. territories. Despite these declines, the obesity prevalence among children aged 2-4 years in WIC remains high compared with the national prevalence of 8.9% among children aged 2-5 years in 2011-2014. Continued initiatives to work with parents and other stakeholders to promote healthy pregnancies, breastfeeding, quality nutrition, and physical activity for young children in multiple settings are needed to ensure healthy child development.