Background Policies to promote healthy eating in young children appear promising, but are largely untested. Recently, South Carolina implemented mandatory nutrition standards governing child-care centers serving low-income children. Objective This study evaluated consistency with the standards before and after the policy took effect. Design This study evaluated consistency with the nutrition standards in South Carolina, using North Carolina--a state not making policy changes--as the comparison. The research team conducted assessments in a longitudinal sample of centers and a cross-sectional sample of children before and approximately 9 months after the standards took effect. Participants/setting Trained observers recorded foods and beverages served to 102 children from 34 centers in South Carolina and 90 children from 30 centers in North Carolina at baseline. At follow-up, the research team observed 99 children from 33 centers in South Carolina and 78 children from 26 centers in North Carolina. Intervention The policy was implemented in April 2012 and included 13 standards governing the nutritional quality of foods and beverages served to children, and staff behaviors related to feeding children in care. Main outcome measures The outcome was consistency with each standard at follow-up in South Carolina compared with North Carolina, controlling for baseline consistency and other covariates. Statistical analyses performed Logistic regressions were conducted to evaluate consistency with each standard, adjusting for baseline and potential confounders. Results Compared with North Carolina, centers in South Carolina were more likely to be consistent with the standard prohibiting the use of food as a reward or punishment (odds ratio=1.22; 95% CI 1.11 to 1.61; P=0.03). Two centers in South Carolina met all 13 standards at follow-up compared with none in North Carolina. No other differences were observed. Conclusions New standards modestly improved nutrition practices in South Carolina child-care centers, but additional support is needed to bring all centers into compliance with the current policies. (author abstract)