This paper investigates the acquisition of compound vs. phrasal stress (hót dog vs. hot dóg) in English. This has previously been shown to be acquired quite late, in contrast to recent research showing that infants both perceive and prefer rhythmic patterns in their own language. Subjects (40 children in four groups the averages ages of which are 5;4, 7;2, 9;3 and 11;6 and 10 adults) were shown pairs of pictures representing a compound word and the corresponding phrase. They heard a prerecorded tape with the names of the items, and were asked to indicate which one they heard. In addition to 9 real compounds and corresponding phrases, 9 novel compounds were presented (rédcup = invented type of flower vs. red cúp). A gradual increase in overall correct scores until age twelve was found along with a significant effect of real vs. novel compounds (p < 0·001), and an overwhelming tendency for the younger children to prefer compounds regardless of stress. We conclude that the results are due to the slow development of the ability to use prosodic information to override a strong lexical bias.