Between 1998-2002, Cotton Incorporated and the Insecticide Resistance Action Committee (IRAC-US) sponsored a monitoring program to assess the extent of pyrethroid resistance in bollworm populations throughout the mid-south/southeastern U.S. In 2003, an opportunity to extend this monitoring effort into the mid-Atlantic States was provided through a collaborative research project sponsored by the United States Department of Agriculture, Cooperative State Research, Education, and Extension Service. Although the major emphasis of this project is to contribute research and marketing information towards sustaining diversified vegetable farms in the northeast by advancing IPM for sweet corn cropping systems, one objective is to assess pyrethroid resistance of immigrating corn earworm (alias: bollworm, Helicoverpa zea) populations. Most (82%) of sweet corn is treated with insecticides to control three major lepidopterous pests (i.e., European corn borer, corn earworm and fall armyworm). The corn earworm (bollworm) is unique among these 3 pests because of the heavy reliance on pyrethroids for control. The 2002 commercial production recommendations used in VA, MD, DE, PA and NJ include 6 insecticide formulations: 5 of these 6 are pyrethroids. Numerous studies have reported pyrethroid resistant bollworm populations in the southern U.S. The 1998-2002, Cotton Incorporated Project generated data suggesting that bollworm populations throughout the mid-south/southern U.S. have become more resistant to the effects of pyrethroid insecticides. Furthermore, resistance in some of the more northerly locations may be due to immigration from more southern locations. It was hypothesized that emigrants from those populations affect earworm control in sweet corn in the northeast. Corn earworm populations throughout VA, DE, PA, MD, and NJ were evaluated for resistance to pyrethroid insecticides during the 2003-2005 study period. Results generated by this 3-year study will be reported.