Ethephon was applied at rates of 0.0, 0.5, 0.75, 1.00, and 1.25 lbs (AI)/a to cotton at the time of early squaring to determine its impact on initiation of pink bollworm, Pectinophora gossypiella (Saunders) infestations and on yields. All treatments significantly reduced the numbers of 1/3-grown or larger squares for up to 10 days following treatment. Numbers of flowers were reduced in ethephon-treated plots as compared to the untreated controls (for up to 16 days). Thereafter, flowering in treated plots equaled or exceeded flowering in control plots. Node of the first fruiting branch and node of the first pink bollworm-infested cotton boll in ethephon-treated cotton was delayed. Cotton yields in plots treated with 0.5 and 0.75 lb (AI)/a were not significantly different from those in untreated cotton plots, but yields were reduced as compared to the controls in plots treated with 1.00 and 1.25 lb (AI)/a of ethephon.