Sediment samples from the New Bedford Harbor Superfund Site, New Bedford, MA, were stabilized/solidified using the following binders: portland cement, Portland cement with a proprietary additive, and a proprietary binder system. Comparison of contaminant masses released during sequential batch leaching of stabilized/solidified sediment and untreated sediment showed that stabilization/solidification reduced the leachability of some but not all metals investigated. The amounts of metal leached from stabilized/solidified sediment relative to the mass leached from untreated sediment were reduced by factors of 10 to 37, 1.2 to 2.6, 4.3 to 28, and 9.0 to 14 for cadmium, chromium, lead, and zinc, respectively. Copper and nickel, however, were mobilized by stabilization/solidification. The amounts of copper and nickel leached from stabilized/solidified sediment relative to the mass leached from untreated sediment were increased by factors of 20 to 23 and 9.6 to 17 for copper and nickel, respectively. Desorption isotherm analysis of sequential batch leach data showed that solidification/stabilization processing of this sediment altered the mechanisms controlling metal leaching.