Studies were conducted at the Winnsboro (Macon Ridge) and St. Joseph locations of the Northeast Research Station to determine the effectiveness of several Bacillus thuringiensis (Bt) based insecticides, efficacy of resistant cotton strains treated with Bt insecticides at two application volumes and the potential of transgenic Bt cotton in controlling the bollworm/tobacco budworm complex (BW-TBW). Data resulting from these studies indicated that all Bt insecticides were effective in reducing BW-TBW square damage below that observed in untreated plots. However, these products did not provide satisfactory control under moderate to heavy infestation densities. Among the cotton strains tested at the Macon Ridge location, La 850082 had significantly fewer BW-TBW damaged squares, fewer BW-TBW live larvae, significantly less boll weevil damaged squares and produced significantly higher yields than Gumbo 500 or Deltapine 51. At the St. Joseph location, La 850082 had significantly less boll weevil damaged squares, significantly less live BW-TBW larvae per 10 row ft and produced significantly higher yields than Gumbo 500. Applying Dipel ES in 10 or 11 GPA at 1.5 pints (form)/acre for BW-TBW control was not significantly better than applying Dipel ES in 5 or 6 GPA. Transgenic (Monsanto Line 81) Bt cotton had significantly less BW-TBW square damage and terminal damage/10 row ft than untreated Coker 312 and provided control equal to that observed in Coker 312 treated with a pyrethroid.