Our data show that lead levels rise during this period,peak-ing around age two.Despite this being well known to public health ocials,implementation of these testing recommendations is far from universal.Often, the children least at risk are the most likely to be tested early, and those most at risk do not get tested until well after their period of greatest risk.In addition to the CDC recommendations, many school districts, including Chicago Public Schools, require children to have had a lead test no more than a year before their matriculation.Again, this requirement may not always be adhered to and misses the most dangerous window the first two years of the child's life|for lead poisoning.Many of the most vulnerable children are not getting tested early enough.Screening of blood lead levels in children identies cases but does not prevent their occurrence. Primary prevention requires that older housing units comply with lead safety standards before they are occupied by children. Though screening and primary prevention work are complementary,the latter is recognized to be more important and far more cost-eective in the eort to eliminate lead poisoning [19].