The U.S. Environmental Protection Agency identifies fluvial sediment as the single most widespread pollutant in the Nation's rivers and streams, affecting aquatic habitat, drinking water treatment processes, and recreational uses of rivers, lakes, and estuaries. A significant amount of suspended-sediment data has been produced using the total suspended solids (TSS) laboratory analysis method. An evaluation of data collected and analyzed by the U.S. Geological Survey and others has shown that the variation in TSS analytical results is considerably larger than that for traditional suspended-sediment concentration analyses (SSC) and that the TSS data show a negative bias when compared to SSC data. This paper presents the initial results of a continuing investigation into the differences between TSS and SSC results. It explores possible relations between these differences and other hydrologic data collected at the same stations. A general equation was developed to relate TSS data to SSC data. However, this general equation is not applicable for data from individual stations. Based on these analyses, there appears to be no simple, straightforward way to relate TSS and SSC data unless pairs of TSS and SSC results are available for a station.