The present study investigates infants’ sensitivity to word boundaries in fluent speech contexts. Using the headturn preference procedure, the first experiment demonstrated that 101/2‐month‐old American infants listened significantly longer to passages in which artificial 1‐s pauses were inserted at word boundaries, as opposed to between syllables within words. A second experiment examined the possibility that word‐stress patterns affect infants’ sensitivity to word boundaries in fluent speech. New groups of 101/2‐month‐olds were tested on new sets of passages. One group received passages with pauses at word boundaries or within words for words having a strong‐weak (SW) stress pattern. Another group received similarly arranged passages but the pauses involved words having a weak‐strong (WS) pattern. If infants use the onsets of strong syllables as cues to word onsets, they might be expected to prefer between‐word pauses in the SW passages but within‐word pauses in the WS passages, In fact, in both cases infants listened significantly longer to passages with between‐word pauses. These results suggest that infants at this age may not rely heavily on word‐stress patterns in locating word boundaries in fluent speech. [Work supported by NICHD and NIDCD.]