We present relationships between the nondestructive measurement of acoustic compressional wave velocity and grain size and show that velocity can be used to assess some physical properties of glacio-marine sediments. For coarse-grained sediments, an increase in velocity is associated with an increase in the percentage of this size range. Within the fine-grained sediment size range, velocity is not an accurate predictor of grain-size. A median grain size of 4 mu m and a sand content of 15 % are the limiting factors that distinguish this fine-grained behavior from coarsegrained behavior. However, in fine-grained glacio-marine sediment, the percent of sand (grain size > 63 mu m), can be predicted by compressional wave velocity. Therefore, with further refinement, acoustic velocity shows some potential as a predictor of grain size for marine sediments.