The objective of the research was to evaluate the acute toxicity of bulk sediment vs. pore water or elutriate to fathead minnows (Pimephales promelas), cladocerans (Ceriodaphnia dubia), amphipods (Hyalella azteca), and oligochaetes (Lumbriculus variegatus). A total of 29 different samples from seven sites were used for this analysis. In most instances, pore water was more toxic than corresponding elutriate. Based on the results of the assays, pore water, but not elutriate, was an effective test fraction for predicting the presence of bulk sediment toxicity; however, there were a number of observations of pore water toxicity in the absence of bulk sediment toxicity. Data from the study concerning the sensitivity of Pimephales promelas, Hyalella azteca, and Lumbriculus variegatus to bulk sediment vs. pore water or elutriate suggest that upper-water-column species are inappropriate organisms for use in bulk sediment tests focused on evaluating in situ toxicity to benthic species. Hyalella azteca was the most sensitive and Lumbriculus variegatus the least sensitive species evaluated.