The potential of biosolid colloids to transport metals associated with organic-waste amendments through subsurface soil environments was investigated with leaching experiments involving undisturbed soil monoliths. The monoliths (25 cm in height and 18 cm in diameter) were carved from the upper solum of an Alfisol, a Mollisol, and an Entisol in the Bluegrass region of Kentucky. Biosolid colloids were fractionated from two municipal wastes (lime-stabilized/LSB, and aerobically-digested/ADB), and a poultry-manure (PMB) organic waste and applied onto the monoliths at a rate of 0.7 cm/hr. Eluents were monitored for colloid and Cu, Zn, Pb, Cd, and Cr concentrations over 16-24 pore volumes of leaching. Colloid-free solutions with metal concentrations similar to those of the biosolid colloids were used as controls. The results indicated significantly higher (up to 2 orders of magnitude) metal elutions in association with the biosolid colloids in both, total and soluble fractions, over the control treatments. Eluted metal loads varied with metal, colloid, and soil type, following the sequences Zn = Cu > Cr > Pb = Cd for metals, and ADB > PMB > LSB for colloids. The elution of significant soluble metal loads in association with the biosolid colloids is attributed to increasing organic-metal complexation and exclusion processes, and emphasizes their importance as contaminant carriers and facilitators. Metal elution was generally enhanced by decreasing pH and colloid size, and increasing organic carbon content. Breakthrough curves were mostly irregular, showing several maxima and minima as a result of preferential macropore flow and multiple clogging and flushing cycles. Soil- and colloid- metal sorption affinity were not reliable predictors of metal attenuation/elution loads, underscoring the dynamic nature of transport processes. The findings demonstrate the important role of biosolid colloids as contaminant carriers and the risk of underestimating groundwater quality impacts in areas receiving heavy applications of biosolid waste amendments.