This investigation studied the conditions under which the function words of grammar are omitted or confused in aphasic speech. Twenty-seven Broca’s aphasics and 23 fluent (Wernicke and amnesic) aphasics took part in Experiment 1, which consisted of: (a) a word-span repetition test, where the subjects repeated grammatically unrelated, equally-stressed, 3-word sets; and (b) a sentence repetition test, where four- and five-word sentences were delivered by the examiner with normal conversational intonation. Compared to Broca’s aphasics of equal severity, the fluent aphasics were at a disadvantage in their span for repetition of word lists, while on the sentence repetition test, initial unstressed function words were more frequently omitted by Broca’s aphasics than by fluent aphasics. Experiment 2 tested the hypothesis that stress and position of function words, instead of word quality, determine whether words are dropped or retained in speech. One Broca’s aphasic repeated a series of 3-word phrases, consisting chiefly of sentences, delivered to him in normal conversational intonation. The results confirmed the hypothesis. In Experiment 3, these results were retested on a group of 10 Broca’s and 12 fluent aphasics, and again the hypothesis was confirmed. It was concluded that the prosodie characteristics of grammatical function words determine whether they are lost or retained in agrammatic speech.