The effect of burial on natural assemblages of benthic invertebrates was investigated using SCUBA techniques in Buzzards Bay, Massachusetts. Various thicknesses of sediment, free of macrofauna, were used to cover the bottom and its natural fauna within the constraints of small boxes and tubes. The taxa and number of organisms escaping this burial were determined by partitioning the containers into vertical sections. Most animals common to a soft-bottom community could escape a burial of 5 to 10 cm. but at depths of about 30 cm none even attempted to crawl up through the column of burying sediment. We suggest that "overburden stress," a measure which relates bulk density and burial depth, reaches a critically high value above which the animals cannot initiate an escape response.