We use a social network approach to examine how work and friendship ties in a university research group were associated with the kinds of media used for different kinds of information exchange. The use of electronic mail, unscheduled face-to-face encounters, and scheduled face-to-face meetings predominated for the exchange of six kinds of information: Receiving Work, Giving Work, Collaborative Writing, Computer Programming, Sociability, and Major Emotional Support. Few pairs used synchronous desktop videoconferencing or the telephone. E-mail was used in similar ways as face-to-face communication. The more frequent the contact, the more “multiplex” the tie: A larger number of media was used to exchange a greater variety of information. The closeness of work ties and of friendship ties were each independently associated with more interaction: A greater frequency of communication, the exchange of more kinds of information, and the use of more media. © 1998 John Wiley & Sons, Inc.