This paper discusses the use of Computer Supported Cooperative Work (CSCW) techniques for computer-aided learning (CAL); the work was started in the context of project Nestor, a joint effort of German universities about cooperative multimedia authoring/learning environments. There are four major categories of cooperation for CAL: author/author, author/learner, tutor/learner, and learner/learner. In GROUPIE (Group Interaction Environment), a generic support system which was carried out in the Nestor project, a common model and taxonomy of cooperation was established; features include universal development support and a runtime support system. In this system, cooperation is viewed as an aggregate of two lower-level concepts, interaction and coordination. CoopEC (cooperating within the European Community learning domain), an example of CAL-specific courseware, teaches about the EC and features a cooperative problem solving process; this software includes a questionnaire, a multitransition between private and group learning, flexible coupling modes, and both online conferencing and asynchronous document exchange. A more liberal approach to commercial courseware is the authoring system, Nestor-ADP, which consists of cooperation-transparent tools, cooperation-aware tools, and the cooperation-aware lifecycle support environment, DIRECT. In DIRECT, the encompassing graphical user interface supports the cooperative construction of complex, hierarchically structured issue-position argument graphs. In general, two areas of cooperation support are distinguished: author/author cooperation, which involves multiple cooperation-aware tools and learner/side cooperation, which must be supported by generic development support for cooperative courseware. (AEF)