A summer food habit study was conducted on 300 specimens of the black sculpin, Cottus baileyi Robins, collected from the upper South Fork Holston River and four tributaries in southwestern Virginia from July to October 1966. Frequency of occurrence, average number, and percent of total were determined for all organisms occurring in the stomachs. Analysis of stomach contents revealed a diet consisting almost exclusively of immature aquatic insects encompassing a wide range of morphological and behavioral differences. Cottus baileyi fed throughout the daylight hours taking whatever was available. Forage ratios ranging from 0.1 to 10.3 were determined for a selected group of insects that represented a wide diversity of habits. Baetis, Pseudocloeon, Antocha, and chironomids had forage ratios greater than 1.0. Baetids and chironomids were the most important food items in the diets of all sizes of fish. Habits of insects largely determined the extent they were preyed upon by C. baileyi.