Residues from the high explosives, 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5- trinitro-1,3,5-triazine (RDX), on military training ranges are a potential source of groundwater contamination. Colloids are postulated to mediate transport of these explosives. Therefore, the objective of this study was to identify potentially mobile soil fraction(s) exhibiting the strongest interactions with TNT and RDX. Test soils represented a range of properties and environments: Catlin silt loam (fine-silty, mixed, mesic, superactive Oxyaquic Argiudolls), Benndale fine sandy loam (coarse-loamy, siliceous, semiactive, thermic Typic Paleudults) and Kenner muck (euic, thermic, Fluvaquentic Medisaprists). The water-dispersible clay fraction (WDC) of each soil was extracted and characterized. Sub-samples of WDC were treated to remove organic matter (OM) (peroxide treatment), amorphous iron oxides (oxalate treatment), and free iron oxides (dithionite-citrate treatment). After lyophilic drying, whole soils and treated clays were used in batch partitioning studies with TNT and RDX. Results indicated increased sorption of explosives by WDC compared to soils, and a decrease in adsorption of both explosives when OM was removed. When OM was present, the effect of amorphous iron removal on sorption of TNT and RDX differed. Oxalate extraction of OM-containing clay increased sorption of TNT, but decreased sorption of RDX. When partition coefficients were normalized to organic carbon content, it was observed that phyllosilicate clays also contributed to TNT adsorption and partition coefficients were affected by the clay mineralogy. Results of this study demonstrate that colloidal OM facilitates movement of RDX, while OM and clays facilitate movement of TNT.