A regional, two-year project sponsored by Cotton Incorporated and the Arizona State Support Committee was initiated in 1994 to determine action thresholds for management of Bemisia tabaci (Gennadius) in cotton using chemical insecticides. This cooperative study involved Cotton Incorporated, the Universities of Arizona and California, Riverside, Texas A&M University and the USDA-ARS, Western Cotton Research Laboratory. Replicated field trials were conducted in 1994 at sites in Maricopa and Yuma, AZ, Bakersfield and Brawley, CA, and Weslaco, TX using a standard set of protocols. Trials were repeated in 1995 at all locations except Bakersfield, CA.