A study was conducted in 1996 to investigate the dynamics of interplant competition among equally-spaced cotton plants grown at four plant population densities (15.50, 3.88, 1.72, and 0.97 plants/m²). Plant growth was monitored weekly to determine when competition among neighboring plants began. Results indicated that interplant competition commenced shortly after adjacent plants made physical contact within and across the row. Results of this study may be used to test physiological cotton growth simulation models.