Intact wetlands are effective in retaining excess nutrient runoff from agricultural systems thereby mitigating eutrophication and toxic algal blooms in aquatic systems. In southern Canada approx. 70% of intact wetlands have been drained for agricultural purpose. Drainage of wetlands is a leading cause for phosphorus (P) pollution downstream because it mobilizes P that has been sequestered for decades in the organic and inorganic phase of sediments and soils. During the past two decades, there has been an increased effort to restore wetlands and their biogeochemical function to retain nutrient runoff from agricultural fields. However, the biogeochemistry of P retention in restored wetlands is largely unknown. We quantified different geochemical soil phosphorus pools in restored and intact wetlands in Ontario and Manitoba using Hedley sequential fractionation. In addition, we analyzed the oxygen isotope composition of 1M HCl extractable phosphate to assess to which degree P has been biologically cycled in these systems. Our results indicate that P in restored wetlands is stored mainly in labile forms, whereas in intact wetlands it is stored mainly in more stable forms. These findings suggest that given enough time labile P forms in restored wetlands will become stabilized in its organic form by iron and aluminum oxides and in its inorganic form by calcium precipitates. In both regions, phosphate in soils from restored wetlands showed consistently higher ?18O values compared to phosphate in soils from intact wetlands, indicating a lower degree of enzymatic hydrolysis of organic P in soils of restored wetlands.