The techniques, procedures, and principal findings of 15 different experiments in a research program on interactive communication are summarized in this paper. Among the principal findings reported are that: problems are solved faster in communication modes that have a voice channel than in those that do not have a voice channel, modes of communication that have a voice channel are much wordier than those that do not have a voice channel, the wordiness of voice modes of communication appears to be due to the fact that it is so easy to talk rather than to the lack of a hard copy to which one can refer at will, and for none of the many problems tested is there any significant advantage of face-to-face communication over communication by voice alone. Other findings reported in the paper relate to communication by persons of diverse abilities, the effect of interrupt capability on communication, the unruliness of natural communication, and the use of restricted vocabularies for communication purposes. (Author/FL)