The purpose of this study was to determine the composition of the benthic fauna near the mouth of Delaware Bay. One hundred and five species were collected and identified from 277 grab samples. A sediment sample was also collected at each of the stations. Faunal density was low with the number of individuals rarely exceeding 10/0.1 m2. Species were ranked according to number of individuals; the nine top species comprised 83.4% of the fauna. The top three species, Tellina agilis, Gemma gemma, and Nucula proxima, comprised 65.2% of all the individuals collected. A high percentage of the species (41.9%) occurred in two samples or less. The six most frequently collected species were compared with six sediment classes based on weight percentage of siltclay. Protohaustorius wigleyi and Trichophoxus epistomus were found mainly in less than 10% silt-clay. Tellina agilis and Ampelisca verrilli were transitional between the pure sand and mud facies. Nucula proxima and Heteromastus filiformis were members of a high silt-clay facies (<50% silt-clay). Diversity values were significantly greater (.05) in the low silt-clay sediments (0–25% silt-clay) than in the high silt-clay sediments (> 25% silt-clay). The relative dominance (redundancy) was not significantly different in any of the sediment types.