Two indices were used to quantify the aggregation of cotton arthropods: the parameterKof the negative binomial distribution and Morisita's index of dispersionIδ. Using frequency distribution data the average values of these indices were calculated. In general there was close agreement betweenKandIδ.Cotton fleahopper,Pseudatomoscelis seriatus(Rueter), nymphs were more aggregated than fleahopper adults. A greater degree of aggregation was observed for boll weevil,Anthonomus grandisBoheman, eggs than for boll weevil adults. Bollworm,Heliothis zea(Boddie), and tobacco budworm,H. virescens(F.), eggs exhibited more aggregation thanHeliothisspp. larvae. Aggregation continued to decrease as theHeliothisspp. larvae became full grown. Among the predatory cotton arthropods, lady beetles and minute flower bugs,Oriusspp., displayed the greatest amount of aggregation. Big-eyed bugs,Geocorisspp., were less aggregated and the spatial distributions of spiders were the least aggregated of the predatory arthropods.