Application of soluble phosphates is emerging as a cost-effective remediation technique for immobilizing lead and reducing the risk of contaminated soil. The impact of the phosphate treatment on soil microbial communities that sustain the terrestrial ecosystem and soil productivity is largely unknown and has been insufficiently evaluated. This study was conducted to assess the alteration of soil microbial properties induced by in situ phosphorus treatments. Three areas in the Jasper County Superfund Site, southwest Missouri were selected for field experiments; each undergoing a different type of treatment. Experimental sites were designated as the Urban Soil treatment plots, the Mill-waste treatment plots, and the Mine-waste treatment plots. Plots at the Urban site were treated with phosphoric acid at a rate of 10g/kg soil through surface application, pressurized injection, and incorporation with roto-tilling. The Mill-waste site also received phosphoric acid applied at rates of 10g/kg and 7.5g/kg soil; while the Mining-waste site was treated with five different organic amendments (OA) ranging from 125 to 250 dry tons per hectare. Assessments of soil microbial parameters included: microbial diversity by Denaturing Gradient Gel Electrophoresis (DGGE) and BioLog techniques; culturable microbial populations; microbial biomass by total organic carbon and nitrogen measurements; and acid and alkaline phosphatase activities. Results demonstrated that phosphorus treatments did not negatively affect the original microbial diversity and population. Combined with the reduction in bioavailability of Pb and the accompanied decrease in Pb exposure hazard to communities in that area, the application of phosphorus can be considered beneficial.