BACKGROUND To meet the national goal of 90% immunization levels in 2 year olds, both the public and private sectors must achieve optimal standards for immunization delivery. This study investigated differences in characteristics of children receiving immunizations from public and private providers and assessed parental attitudes about prevention, perception of barriers, and attitudes about vaccines. METHODS Data are from a 1994 statewide household survey of 3,813 parents of children between the ages of 3 and 24 months. Information on the percentage of children up-to-date for recommended diphtheria and tetanus toxoids, pertussis, oral polio, measles, mumps, and rubella vaccines was based on parent-held immunization records (72%) and parental recall. RESULTS The percentage of children up-to-date for their immunizations was higher for those attending public clinics (59.8%) than those at private offices (53.8%). Users of the public system were more likely to be Hispanic, not to have graduated from high school, to be < or = 100% of poverty, never married, and unemployed. These parents also were significantly more likely to wonder about the safety and efficacy of vaccines and to have their child's immunization record. Multiple logistic regression showed that possession of an immunization record accounted for differences in immunization levels. CONCLUSIONS Public clinics can achieve immunization levels in their pediatric clients comparable to those for children in the private health sector. Levels in both public and private sectors are well below 90% and need to be improved.