This project aimed to identify factors that could substantially influence Bt efficacy in, transgenic cotton. Cry1Ac protein concentration in cotton leaves was measured quantitatively, using a commercial ELISA assay. Previous research suggested that Bt efficacy was, compromised to some extent when environmental stresses were imposed on transgenic, plants. Experiments were designed to investigate a range of factors that may affect Bt, efficacy, including: crop nutrition, planting density, light intensity, water management, soil, type, herbicides, temperature, soil fertility, growth regulators, and cotton cultivars.