Although Louisiana is usually thought of as a state that receives above normal rainfall, certain parts of the state can be very dry during the agriculturally critical summer months. This is especially true of the northwest part of Louisiana where 20% of the cotton is grown. One major limitation to cotton productivity in this area is water. Forty-four-year average rainfall (1956-1999) for the critical months of June, July and August recorded at the Red River Research Station in Bossier City, Louisiana was 4.5, 3.7, and 2.8 inches, respectively. In 1956, a long-term irrigation study was initiated at the station to determine whether or not yield improvements in cotton with irrigation would be consistent enough to justify the expense of establishing an irrigation system. This study was conducted from 1956 until 1983. During the 28 years of this study, irrigation response ranged from an increase of 2087 pounds of seedcotton in 1956 to a loss of 295 pounds of seedcotton in 1983. However, the average significant increase of 347 pounds of seedcotton per acre over the 28-year period of this study and the fact that irrigation increased yields 18 of the 28 years indicates that, more often than not, irrigation would be beneficial in Northwest Louisiana.