Two nonirrigated field studies were conducted from 1988 through 1991 at Stoneville, Mississippi to determine the effect of crop rotations on yield of cotton grown in 30-inch row spacings in conventional and ridge-till production systems. Cotton (DES-119) was grown in (1) continuous monoculture, (2) in rotation with soybean, and (3) in rotation with grain sorghum as part of a larger study that also included monoculture and similar rotations of soybean and grain sorghum. The conventional production study was conducted on a Dundee silty clay loam, whereas the ridge-till study (no spring preplant tillage) was conducted on a Tunica clay. Weed control and other production inputs were the same for the two studies. In each study, mean seed cotton yields from monoculture cotton and from cotton rotated with soybean were statistically similar but significantly lower than the mean seed cotton yield from cotton rotated with grain sorghum. For the conventional 30-inch production system, seed cotton yields from cotton rotated with grain sorghum (2013 lb/acre) averaged 10% higher than from monoculture cotton (1822 lb/acre) and 1% higher than from cotton rotated with soybean (1792 lb/acre). Similarly, in the ridge-till 30-inch system, seed cotton yields for cotton rotated with grain sorghum (2122 lb/acre) averaged 0% higher than from monoculture cotton (1770 lb/acre) and 14% higher than from cotton rotated with soybean (1862 lb/acre). For farm enterprises that have adequate acreage available and program flexibility, a rotation of cotton and grain sorghum would enhance cotton yields in 30-inch production systems by 10-0% over that expected from monoculture cotton. A similar rotation with soybean would not enhance cotton yield but may be beneficial in other ways (weed control or replant considerations).