Three studies of cooperative problem solving among university students examined how to design effective computer-based support for collaborative learning in distance education. The first was a questionnaire study of 150 Open University students who had participated in three different courses in physics and mathematics. Its aim was to determine students' participation in and preferences for cooperative work in their courses. The main finding was that although students expressed a preference for working alone, many participated in collaborative work in their courses and regarded such activities as helpful. More detailed investigation was needed to determine the nature of collaborative activities in which these students engaged and the ways in which they found them helpful. An observational study of group activities at summer school and a comparison of the use of two different kinds of interface for supporting synchronous cooperative problem solving were then conducted. The characteristics of successful divisions of labor observed in noncomputer-based activities suggested that one issue related to designing computer support for such problem solving is how to design appropriate tools and representations for joint activity. (Appendixes include 28 references and 5 figures.) (YLB)