This study examined the relative effects of homogeneous versus heterogeneous ability grouping on performance and attitudes of students working cooperatively during interactive videodisc instruction. After two cooperative training sessions 80 fourth through sixth grade students, classified as high and low ability, were randomly assigned to treatments. Students completed a level II interactive videodisc science lesson about whales, an achievement test, and an attitude questionnaire. The amount of instructional time for each group was also recorded. Results revealed that homogeneous low ability groups scored significantly less than the other three groups, while the difference between achievement of high ability students in homogeneous and heterogeneous groups was not statistically significant. Homogeneous low ability groups consistently used more instructional time than the other groups, whereas homogeneous high ability groups used the least amount of time. Low ability students in heterogeneous groups had significantly better attitude scores than their high ability groupmates. Implications for the collaborative use of level II videodiscs are discussed. (29 references) (Author/BBM)