Cultivar entries in the Louisiana early-season and medium-season cotton variety tests were planted in conventional and reduced tillage systems on a Norwood silt loam soil at the Dean Lee Research Station to determine if varieties interacted with tillage systems to affect performance. There were 24 cultivars in the early-season test and 17 cultivars in the medium-season test. Beds were prepared in the previous year and planted to wheat as a cover crop for both tillage regimes. Burn-down herbicides were applied to the wheat in March and again in May. Beds were reversed twice in the conventional tillage plots using disks and lister plows, followed by knocking down beds for planting with a do-all. Reduced tillage plots received no cultivation in preparation for planting. Yields were higher in the reduced tillage plots in both early-season and medium-season variety tests. There were also differences among cultivars in each test. There was no overall significant (p=0.05) interaction between tillage systems and cultivars affecting yield; however, the interaction between tillage systems and varieties in the medium-season variety test was significant at a probability level of 12%. This may indicate that a relatively small interaction exists between tillage systems and varieties that affects yield. The interaction between tillage systems and cultivars affecting plant height in the early-season test was significant at a probability level of 8%.