Many cotton growers are concerned that relying too heavily on Roundup (glyphosate) will lead to future problems with weeds becoming resistant to this herbicide. The potential for resistance is very real, as shown by the increasing resistance problems with Roundup Ready crops in the US, and emerging problems with glyphosate resistant ryegrass and awnless barnyard grass in the Australian cotton growing area. This paper discusses these issues and explains the value of the approach used in the Crop Management Plans of Roundup Ready and Liberty Link cotton for managing the development of resistance