The growth of the lnternet is expanding the opportunities for professional collaboration and collaborative learning by removing geographic and time-related barriers to such activities. Taking advantage of the opportunities that are now presenting themselves involves creating a shared virtual workspace by means of one of the growing range of Computer-Mediated Communications (CMC) systems. This article discusses the types of CMC systems now available for supporting collaboration over the Internet. It distinguishes four different frames of references in terms of which the use of CMC systems have been discussed in the contemporary literature. The implications of the adoption of each frame of reference are discussed. The article concludes that the initiators of collaborative activities on the lnternet are to obtain the greatest benefit from use of collaborative tools then they need to avoid having their way of understanding the use of CMC systems confined to a single frame of reference.