In field studies combinations of herbicides applied preplant, preemergence, or postemergence were compared for control of prickly sida (Sida spinosa L.) in cotton (Gossypium hirsutum L. ‘Stoneville 7A’). All plots received an application of α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) incorporated into the soil prior to planting. Additional preemergence applications increased control of prickly sida 94% with 1,1-dimethyl-3-α,α,α-trifluoro-m-tolyl)urea (fluometuron) and 53% with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron). Seven postemergence treatments evaluated were at least partially effective in controlling prickly sida. However, trifluralin applied preplant followed by fluometuron applied preemergence gave the most effective prickly sida control in combination with all post-emergence treatments. Prickly sida populations of 130 plants per square meter competed with cotton all season and reduced yield 41 and 37% in 1969 and 1970, respectively. Prickly sida did not appear to affect cotton grade or staple length.