An Amberlite XAD-4 polymeric resin technique was used to independently evaluate the contribution of easily desorbable hydrophobic organic contaminants (HOCs) to overall sediment toxicity. After incubation with native sediments, XAD resins were extracted with the organic solvents, and material captured in the extracts amended back unto reference sediment either intact or after fractionation to isolate different compound classes. A variety of bioassays utilizing fish embryos and larvae and invertebrates exposed to whole sediments, and luminescent bacteria(Microtox®, Mutatox®) exposed to sediment extracts were then used to compare the toxicity of native sediments to reference sediments amended with XAD extracts, and to compare the relative sensitivity of the bioassays used. The data obtained support the use of the XAD method as a tool for toxicity identification evaluation in sediments contaminated with HOCs, the use of Ampelisca abdita as a sensitive indicator of acute sediment toxicity, and the use of Microtox® as a screening tool to obtain a relative estimate of potential toxicity.