This study analyzed predictors of adherence to well-child care visits among 744 Medicaid-eligible infants in Philadelphia. The strongest predictor was having siblings in the home, which significantly decreased adherence. Being an unmarried mother also decreased adherence. Adherence decreased between 6 months and 18 months of age, suggesting efforts are needed to encourage continued adherence as children grow older. Social and educational supports may help improve adherence among at-risk groups like single mothers and those with low prenatal care adherence.