An acoustically invariant one-word segment occurred in two versions of one syntactic context. In one version, the preceding intonation contour indicated that a stress would fall at the point where this word occurred. In the other version. the preceding contour predicted reduced stress at that point. Reaction time to the initial phoneme of the word was faster in the former case, despite the fact that no acoustic correlates of stress were present. It is concluded that a part of the sentence comprehension process is the prediction of upcoming sentence accents.The greater the degree of stress assigned to a word in a sentence, the longer its vowel (or the vowel of its stressed syllable) will be, the higher the relative pitch of the word will be, and, in general, the greater the peak amplitude of its stressed syllable will be (Lehiste, 1970). Words assigned little relative stress in a sentence, on the other hand, tend to have shorter duration, lower relative pitch, and less relative amplitude; further, the vowels in unstressed words often reduce to lal. It is reasonable to expect that words that are longer, louder, and higher pitched should be somewhat easier to comprehend than words that are shorter, softer, and lower pitched and contain reduced vowels; indeed, Lieberman (1963) has shown that this is true of isolated words which are excised from a sentence context. Such differences in ease of comprehension, or intelligibility, should be of importance in the course of sentence processing. The more easily an acoustic representation can be decoded, the more quickly its meaning can be retrieved from the mental lexicon to contribute to the semantic representation being constructed of the sentence.That assigning stress to an item in a sentence will affect the role that item takes in the comprehension process has, in fact, been demonstrated by several recent investigations using the phoneme monitoring technique. In a phoneme monitoring experiment, subjects are asked to comprehend sentences and at the same time to listen within them for the occurrence of a specified word-initial phoneme. Reaction time to the target phoneme in this task has been assumed to be sensitive to momentary processing difficulty during sentence comprehension; it is raised, for instance, by the occurrence immediately prior to the target-bearing word of a low-frequency word (Foss, 1969) or of an ambiguous item (Foss, 1970). Cutler and Foss (in press), investigating the source of faster reaction times to