ANGULAR LEAF SPOT of cotton (Gossy pium hirsutum L.) was first reported in California in 1912 and again in 1929. It had become an established disease of cotton by 1951 and was finally eradicated 10 years later. Its spread was attributed to (1) the introduction of sprinkler irrigation; (2) a 100% carryover of the bacterial pathogen, Xanthomonas Malvaciarium, each year in affected fields; (3) the use of contaminated seed; and (4) use of a highly susceptible variety (Acala 4-4.2). This report analyzes measures leading to final eradication of the pathogen from California cotton fields and points out procedures to control the disease should it reappear in the future.