Plant structure components related to variation in yield between 25 thai cotton fields grown at low plant density were investigated in the cotton growing area of Chaibadan District, Lopburi Province, Thailand during 1994 and 1995. Despite a low contribution of P1 bolls to yield and a high number of sympodia, survival of P1 fruits of the first-ten fruiting nodes together with the change in Height to Node Ratio (HNR) provided a meaningful appraisal of the origin of yield variation between farm plots. The relevance of these criteria was validated with data from an additional 75 plots surveyed in 1993. Standards for predicting yield and adjusting crop management decisions to actual plant structure were generated.