Conservation tillage reduces wind and water erosion and increases water storage in the soil profile, but growers will generally not accept new management practices unless they are profitable. Conservation tillage trials were initiated at dryland and irrigated sites in the Lower Rio Grande Valley of Texas in 1992. The purpose of this paper is to compare lint yields and economics of cotton production in conventional (CT), reduced tillage (RT), and pre-plant no-tillage (PPNT) systems. Three crop rotational schemes were used at the irrigated site and six at the dryland. At the irrigated site within a tillage treatment, rotation effect was not significant. In 1994, lint yields among tillage treatments were not significantly different. In 1993, RT was significantly greater, and in 1995 both RT and PPNT were greater, compared to the others. In 1993, net returns for double crop cotton-corn under PPNT were $106/ha greater than CT; in 1994, $182 greater; and in 1995, $541 greater. At the dryland site, cotton lint yields did not differ in 1993 and 1994. In 1995, yields were significantly lower for CT and significantly greater for cotton following two years sorghum, compared to the other treatments. At the dryland site, net returns for PPNT were $126 greater than CT in 1993; $131 greater in 1994; and $153 in 1995. Data from this study strongly suggests greater profitability in conservation tillage compared to conventional tillage systems. The system, however, requires a much higher level of soil and crop management.