The cabbage maggot, Delia radicum (L.) is an important insect pest of cruciferous crops in upstate New York. This species causes considerable damage to seedlings and young plants by feeding on roots and stems, resulting in plant stand loss and yield loss. Five crucifer accessions (Brassica oleracea variety italica L., ‘Green Comet’; B. oleracea L., ‘Rapid Cycling’ [Crucifer Genetics Cooperative 3–1]; B. oleracea variety botrytis L., a standard cauliflower cultivar ‘Amazing’; B. carinata L.; and Sinapis alba L., ‘Cornell Alt 543’) were evaluated to identify sources and mechanisms of resistance for D. radicum. Of the accessions tested, S. alba Cornell Alt 543 demonstrated reduced oviposition by D. radicum, reduced weights and survivorship of larvae, pupae or adults, and reduced damage to plants. Thus, S. alba Cornell Alt 543 could be a potential source for resistance to be bred into cruciferous crops for control of D. radicum.