This study investigated the effects of positive interdependence and group processing on student achievement and attitude in online learning. Students in three university courses received initial instruction about teamwork skills and cooperative learning and were randomly assigned to one of three treatment groups in each course. The "positive interdependence" and the "group processing" groups received subsequent associated skills training. The "no structure" control group received no additional training. Following the treatment, the "positive interdependence" groups had significantly higher achievement than the "group processing" or the "no structure" groups. There was no significant difference among any of the three groups on student attitude. (Contains 4 tables.)