Early research argued that computer-mediated communication (CMC) had a number of advantages over existing communication media for supporting collaboration. However, a number of papers emerged that began to raise doubts about this positive view. These papers reported difficulties using CMC to support collaboration. Several systems are reported in this special issue that try to overcome these difficulties, either by changing the communication tools or by developing sound social spaces. These systems are important because the right tools and environment are essential; however, recent research suggests that we need to do more than this, because students do not know how to collaborate effectively and they need to develop these skills to use the tools productively. Other papers in this Special Issue suggest ways this might be achieved.