A school-based immunization survey was conducted among the 36 Rochester, NY, elementary schools (n = 5584 children) to determine (1) the vaccination rates at 2 years of age by type of primary care provider and (2) the accuracy of school immunization records (by comparing them with medical charts for children attending hospital-based clinics). These rates varied by provider type from 58% to 86% and were all below the national goal of 90%. In comparison with medical chart review, the school data had error rates of 15%; however, these errors occurred in both directions and were thus unbiased. School-based surveys include children who lack connections to the primary care system. With minimal effort these surveys can help identify populations in need of intervention.