This study identifies the contribution of technologies and weather to cotton yield variation for the period 1964 to 1979 in the Delta Region. Ordinary least squares regression was used to measure the impact of land quality, fertilizer, variety improvement, pesticides and weather effects on state average cotton yields in the Delta Region. In addition, changes in predicted yields were partitioned with respect to weather and technologies. Reduction in input usage in Arkansas has contributed more to cotton yield reductions than weather factors. The opposite is true for Louisiana and Mississippi, where weather played a major role in yield reduction.