Field experiments in three seasons examined the effects of plant population and row spacing on the yield of two cotton cultivars. For the early maturing cultivar, Riverina Poplar, 36 cm rows yielded 18 per cent more than 100 cm rows with no additional benefit being obtained from 18 cm rows. The medium maturing commercial cultivar, Deltapine 16, had the same average yield at all row spacings. The effect of plant population on yield was significant in all row spacings, with populations above 40 plants m-2 in 18 cm rows, above 30 plants m-2 in 36 cm rows, and above 13 plants m-2 in 100 cm rows yielding less. In all experiments, narrow rows and high plant populations had smaller bolls, more barren plants and smaller plants than wide rows and low plant populations. At low yield levels, Riverina Poplar in narrow rows was superior to wide rows and to Deltapine 16 in any row spacing. At high yield levels, Deltapine 16 was superior, particularly in wide rows