Seventy percent of Latino children and 53% of African-American children were fully immunized or up-to-date (UTD) at 3 months of age. At 24 months of age, 42% of Latino children and 26% of African-American children were UTD on their immunizations. Receipt of the first immunizations by 3 months was associated with smaller family size, and evidence of connection to prenatal care. Latino children were less likely to be UTD at 24 months if they obtained well child care from private providers versus public clinics. There was also a trend for Latino children to be less well immunized if they were in health maintenance organizations versus public clinics. African-American children were more likely to be UTD at 24 months if they were UTD at 3 months, had more health visits, and were less likely to be UTD at 24 months if they were on Medicaid versus private insurance.