Bottom Line: This study looked at changes in overweight and obesity among low-income young children enrolled in the food assistance Special Supplemental Nutrition Program for Women, Infants and Children (WIC) from 2010 to 2016. The analysis included 12.4 million children 2 to 4 years old. Obesity declined between 2010 and 2016 to 13.9% from 15.9%; overweight and obesity combined declined to 29.1% from 32.5%. Declines were seen overall and in all age, sex and racial/ethnic subgroups. Reasons for the declines are unknown but could include WIC food package revisions, along with local, state and national initiatives. A limitation of the study is that fewer children were enrolled in WIC in recent years.