This study investigated the following hypothesis: physiological, psychological, and verbal behavior indices of communication apprehension can predict comprehension, perception of speaker credibility, and ratings of speech effectiveness. The stimulus materials were videotapes of the first minute of 85 different students expressing their views on women's liberation. Measurement on all the indices of communication apprehension had been taken on these students as the videotapes were being prepared. Each of these one-minute videotapes was shown to a single receiver who then filled out forms measuring comprehension, perception of source credibility, and rating of speech effectiveness. Results supported the hypothesis that the indices of communication apprehension could predict all the communication effects save one, perception of character. The strongest relationship between the set of communication apprehension variables and the set of communication effectiveness variables indicated that individuals who reported high apprehension experienced much silence in their speech and received low ratings on language facility, vocal characteristics, and general effectiveness.