The Syracuse urban metal mapping and exposure research (SUMMER) project has collected over 3500 soil and 2000 floor dust samples to study spatial patterns and geographic variability of several urban metal pollutants. The results, along with other lines of evidence to be presented, indicate that soil Pb is a strong contributor to childhood lead exposure, perhaps with a significance equal to that of lead-based paint in deteriorating housing structures. The presentation will illustrate this importance, drawing upon detailed soil Pb distribution maps, the spatial patterns of household floor dust loading in Syracuse, and estimates of the external soil fraction (ESF) contained within those dusts calculated from the dilution of the soil tracer elements, Fe and Mn. A strategy will be outlined for use of these geo-referenced environmental data in a probabilistic blood lead prediction model, the IEUBK model. It will address the hypothesis that children's indoor Pb exposure can be predicted from outdoor environmental lead measures and sociodemographic parameters, without indoor dust analyses.