Several states operate universal vaccine purchase (UVP) programs aimed at ensuring adequate immunization of children. Some of these programs have been in operation for many decades. Recently, there has been a great deal of interest in implementing a federal UVP program. It is not clear, however, that such programs can significantly increase immunization levels; many nonfinancial barriers to full immunization exist and would have to be addressed. This paper uses cross-sectional data at the state level to estimate the effect of state UVP programs on the immunization levels of preschool children. The results indicate that states with UVP programs do not have significantly higher immunization rates than do other states. Therefore, it is not likely that a federal UVP program would significantly affect immunization rates.