Dialogue has become a lost art. Most public discourse takes place in the form of unilateral assertions argument or debate. By contrast dialogue can foster the co-creation of meaning among participants. Dialogue is therefore both a communicative and an intensely creative process. Unfortunately the majority of existing research on dialogue fails to take into account Internet-mediated dialogue while conversely most research on Internet-mediated communication focuses on methods of information exchange rather than true dialogue. The present study fulfills two purposes. First it synthesizes much of the existing research on human dialogue emphasizing how cognitive styles and cultural values can influence its effectiveness. Second it relates the results of an analysis of seventeen independent online dialogues and presents a theory of effective Internet-mediated dialogue. This work is addressed to professors and students of communication theory managers seeking to find better ways of dialoguing with clients online participants in Internet-mediated communication of any type and software engineers designing online communication spaces.