When contaminant-enriched soil is used for urban gardening, exposure to contaminants in soils primarily happens in two ways: direct exposure to contaminated soil (such as soil ingestion) or indirect exposure to contaminants from the soil-plant-human pathway. In situ stabilization of contaminants in soil can be achieved through addition of soil amendments. Over the past 9 years, we studied the manipulation of bioaccessibility of soil contaminants in urban brownfields and yard soils via in situ soil amendments and contaminant uptake by food crops grown on several urban brownfield sites slated for community gardens throughout the U.S. The challenges in stabilizing the contaminants via treatments in urban brownfields soils are heightened by unique soil characteristics, poor soil quality, and the presence of co-contaminants. The most common soil contaminant at the brownfields sites and the tested yard soils was lead. We also found elevated arsenic and polycyclic aromatic hydrocarbons at one or more of our test sites. Our research indicates that the potential exposure pathway of concern is the direct exposure of humans to contaminated soils. The pathway from contaminated soil to plant to human is insignificant. Our research has also shown that, in general, concentrations of lead, arsenic, and polycyclic aromatic hydrocarbons in vegetables harvested at test sites were low and contaminants can be diluted by the addition of clean compost. However, the concentrations of contaminant uptake appear to be highly dependent upon soil and other site-specific characteristics. Compost additions help reduce contaminant concentrations in vegetables. Our results indicated that most of the lead and arsenic in soils were not bioaccessible (measured by modified physiologically based extraction test developed by Ruby et al. 1996). In general, soil treatments further reduced bioaccessibility of lead and arsenic, although, these reductions were not always significant. Detailed investigations of the changes in speciation of soil contaminants using X-ray absorption spectroscopy indicated a lack of clear changes in speciation except when the mixtures of soil amendments were added or the ageing of the soil-treatment mixture had occurred. For mildly contaminated soils, a better understanding of underlying mechanisms responsible for the effectiveness of traditionally used in situ stabilization treatments for soil contaminants as well as new and/or improved in situ treatments in the presence of co-contaminants is needed. This understanding will help in developing more practical, safe, and cost-effective alternatives for dealing with the wide-spread, low levels of soil contamination in the U.S. and around the world.