Recent yield advances in cotton (Gossypium hirsutum L.) hive been associated with early fruiting and high harvest index (hi). This study was conducted to examine the effects of plant density in a narrow-row (0.76-m interrow spacing) system on plant morphology, fruiting pattern, and yield of five genotypes that differ in degree of determinacy. ‘Acala SJ-2’, ‘Acala SJC-1’, and 2218, 2280, and 2086 (USDA-ARS Shafter short-season germplasm) were grown in a factorial design at 5, 10, and 15 plants m⁻² in 1984 and 1985. Growth data were collected four times daring the season and fruiting data obtained from plant mapping at the end of the season. Genotypes did not differ in plant height until after anthesis, when the most indeterminate genotype (Acala SJ-2) continued vegetative growth longer than the more determinate genotypes 2280 and 2086. Increasing plant density from 10 to 15 plants m⁻² delayed maturity of the more indeterminate genotypes but had no effect on the shorter, more determinate 2280 and 2086. Genotypes 2280 and 2086 were earlier mataring than the other three genotypes regardless of plant density. Earliness was associated with a lower node number of the first fruiting branch, more rapid production of early main-stem nodes, and increased retention of early fruiting forms. Lint yield decreased 59 kg ha⁻¹ for each O.l-m increase in final plant height between 0.77 and 1.36 m when genotypes were grown at 15 plants per m⁻²; at densities of 5 and 10 plants m⁻², there was no significant relationship between lint yield and plant height across genotypes and years. This research was supported by a grant from the California Dep. of Food and Agric. Cotton Pest Control Board.