guidelines, and they provide public health authorities comprehensive population-based information on immunization rates. A national system of state-based registries that covers all children and that is used by all providers promises the greatest benefit.

A need also exists for a comprehensive and annotated bibliography of studies on immunization practices, which would help providers and public health officials make better use of the research that has already been conducted. The bibliography should focus on studies of who is not immunized and why and of interventions that are succeeding in improving immunization rates.

The nation needs an enhanced, broad-based collaboration between the public health system and private medical practice to meet the primary care needs, including immunization, of preschool children. Although some of what should be done is complex or costly, many simple steps can be taken, often without additional funding. In either case, prompt action is needed to achieve the 1996 goal of up-to-date immunization for 90 percent of 2-year-olds. As the nation debates health care reform, experience with immunization serves as a clear reminder that removing financial barriers is not enough to ensure that those who need care will receive it.