In 1962, Marshall McLuhan envisioned a world in which electric media would extend the human embrace on a worldwide scale and create a new type of global village. Although his vision tends to be interpreted as a technological phenomenon, it is equally, if not more so, a human one. At a time when television and mass media messages dominated the media landscape, it was difficult to see the human communication aspect of media change-the use of media to facilitate human relationships. However, starting with the telegraph and telephone, media environments have gradually come to replace many face-to-face contexts in which interpersonal interactions occur. Utilizing a media ecological perspective, this chapter will describe how mediated contexts facilitate interpersonal human communication and how computers are now being used to initiate, support, and develop communication exchanges between people. Today, interpersonal communication takes place in mediated contexts and software developers are creating social computing tools to facilitate this process. The study of computer-mediated communication (CMC) explores how mediated environments support and extend the process of human communication and social computing examines the tools that facilitate this process.