Perceptual grouping has traditionally been thought to be governed by innate, universal principles. However, recent work has found differences in Japanese and English speakers' non-linguistic perceptual grouping, implicating language in non-linguistic perceptual processes (Iversen, Patel, & Ohgushi, 2008). Two experiments test Japanese- and English-learning infants of 5-6 and 7-8 months of age to explore the development of grouping preferences. At 5-6 months, neither the Japanese nor the English infants revealed any systematic perceptual biases. However, by 7-8 months, the same age as when linguistic phrasal grouping develops, infants developed non-linguistic grouping preferences consistent with their language's structure (and the grouping biases found in adulthood). These results reveal an early difference in non-linguistic perception between infants growing up in different language environments. The possibility that infants' linguistic phrasal grouping is bootstrapped by abstract perceptual principles is discussed. (Contains 3 figures.)