Field and greenhouse experiments were conducted to determine the effects of tank mixing the insecticides carbaryl and dimethoate with sethaxydim and fluazifop on cotton tolerance and large crabgrass control. Tank mixing carbaryl with either sethoxydim or fluazifop resulted in less control of large crabgrass than that obtained with the herbicides applied alone. The antagonism could be overcome by increasing the herbicide application rate. Dimetboate tank mixed with either sethoxydim or fluazifop did not reduce the grass control obtained with either herbicide. Neither the herbicides nor the insecticides applied alone or in tank mixtures resulted in visual cotton injury or affected cotton lint yield or fiber quality.