Studies of speech perception and segmentation in the prelinguistic period, early word production, and patterns of function word omission in early syntax have all recently emphasized the role of the trochaic accentual pattern in English, sometimes positing a universal trochaic bias. We make use of perceptual and acoustic analyses of words and babble from 9 children acquiring English and 5 acquiring French in the late single-word period (13–20 months) to provide a direct test for the existence of such a bias. Neither English nor French infant vocalizations were exclusively trochaic. The iambic productions of American infants were traced to the presence of iambic phrases in the input. Differences between English and French in the acoustic realization of accent in infant vocalizations were also traceable to adult patterns. However, the almost bipolar distribution of trochaic and iambic patterns in the data from English-learning infants was ultimately traceable to the integration of prosodic and segmental patterning in individual child word production templates, themselves arguably the product of an earlier acting articulatory filter.