Due to the utilization of early postemergence treatments of glyphosate on Roundup Ready cotton, the use of preemergence residual herbicides has declined. Glyphosate has no residual activity. Without using residual herbicides, problems such as shifts in weed populations or weed resistance may arise. Therefore, experiments were conducted to determine cotton tolerance when applying pendimethalin with glyphosate and s-metolachlor with glyphosate on transgenic cotton. Experiments were conducted at the Black Belt Branch Experiment Station in Brooksville, MS. Applications were made using a compressed air hooded sprayer system. Applications were made at preemergence, 1-leaf, 4-leaf, and lay-by application timings. Weed control data will be combined with yield data to determine the optimum herbicides and application timing for incorporating residual herbicides into the Roundup Ready system.