The impacts of computer-assisted cooperative, competitive, and individualistic instruction were compared on student achievement and attitudes. Seventy-three eighth graders were randomly assigned to conditions stratified for sex and ability. In all conditions students completed the same computer-assisted instructional unit. The results indicate that computer-assisted cooperative instruction promotes greater quantity and quality of daily achievement, more successful problem solving, and higher performance on factual recognition, application, and problemsolving test items than does computer-assisted competitive or individualistic learning. The girls' attitudes, compared with the boys', were adversely affected within the competitive condition.The instructional use of computers is mushrooming within the United States. The number of personal computers for instructional use in public elementary and secondary schools rose from 31,000 in 1981 to 325,000 in 1983 and is expected to double in each of the next 5 years. This growth of computer technology presents education with several challenges. One is promoting computers' effective instructional use without increasing the isolation and alienation of students. Computer-assisted instruction brings with it the possibility that student interaction with computers may result in less interaction with teachers and classmates. An individualistic assumption has dominated the instructional use of computers. One student to a computer is the usual rule, and computer programs have been written accordingly. Many teachers and software designers automatically assume that all computer-assisted instruction should be structured individualistically. The assumption that