Blood lead (Pb B) was determined in 1232 samples from 831 children in Omaha and correlated with air lead (Pb A) concentrations of 0.02-1.69 microgram/m3 from 1971 to 1977. A bivariate equation for ages 6-18 yr based on these data predicts an increase in Pb B of 1.4 microgram/dl as Pb A increases from 1 to 2 microgram/m3. Pb B increases 7 microgram/dl as the mean values for soil and house dust Pb increase from 100 to 750 microgram/g. Multiple regression analysis shows that the combined effects of air, soil, and house dust Pb account for 21% of the variance of Pb B, with a high intercorrelation of all 3 variables. Since the variance of repeat sampling in individuals accounted for 38% of the total variance of Pb B, approximately 40% is unexplained and requires measurement of Pb from dietary and other sources.