It is generally accepted that filled pauses and urn) indicate time out while the speaker searches for the next word or phrase. It is hypothesized that the more options, the more likely that a speaker will say uh. The academic disciplines differ in the extent to which their subject matter and mode of thought require a speaker to choose among options. The more formal, structured, and factual the discipline, the fewer the options. It follows that lecturers in the humanities should use more filled pauses during lectures than social scientists and that natural scientists should use fewest of all. Observations of lecturers in 10 academic disciplines indicate that this is the case. That this is due to subject matter rather than to self-selection into disciplines is suggested by observations of this same set of lecturers all speaking on a common subject. In this circumstance, the academic disciplines are identical in the number of filled pauses used. It is an unusually glib and articulate person who, on hearing a tape recording or reading a literal transcript of his or her remarks, has not been shocked by his or her apparent verbal clumsiness, characterized often by agrammatic, redundant speech that is interrupted by repeated words, false starts, long pauses, and guttural interruptions such as uh, ah, and um. That such disfluencies are an integral part of the speech production apparatus is suggested by studies of silent and filled (uh, ah, er, and um) pauses, which are based on the hypothesis that such interruptions in the flow of speech are indications of time for the speech production apparatus to search for the next word, phrase, or idea (Rochester, 1973). Such pauses, according to Lounsbury (1954), may be interpreted as indicative of the strength of association between sequential linguistic events. Alternatively, pauses have been interpreted in more cognitive