For sediment transport studies, one describes the transport on a size class by size class basis as a function of vertical height. This requires the suspended sediment size spectrum as a function of depth and time. No in-situ instrumentation determines the full particle size spectrum, but the LISST (Laser In-Situ Sizing and Transmissometry) particle sizer, appeared to meet some of our observational needs. Three LlSSTs were purchased and two mounted on our bottom boundary layer tripods. The third was retrofitted with a settling tube to make it a "LISST-ST." These LISSTs have been deployed at the LEO-IS site off New Jersey in the fall of 1995, and in STRATAFORM in the winter 1996 on the Northern California shelf. Finally, we studied the LISST's response to real sediments from various sites. The sediment was sieved to obtain various sized sediments and the LISST's response to each size class was observed. Also, quantitative calibrations were made to see if the LlSST would integrate the total suspended sediment properly, and these results are currently being written into a paper.