Intake and growth were compared between matched cohorts of infants either breast-fed (BF) or formula-fed (FF) until > or = 12 mo of age. Total energy intake at 3, 6, 9, and 12 mo averaged 0.36, 0.34, 0.35, and 0.38 MJ.kg-1.d-1 (85.9, 80.1, 83.6, and 89.8 kcal.kg-1.d-1) among BF infants vs 0.41, 0.40, 0.39, and 0.41 MJ.kg-1.d-1 (98.7, 94.7, 93.6, and 98.0 kcal.kg-1.d-1) among FF infants, respectively. Protein intake was 66-70% higher in the FF than in the BF group during the first 6 mo. Differences in energy and protein intakes were significant at 3, 6, and 9 mo. Gains in weight and lean body mass were lower in BF than in FF infants from 3 to 9 mo. BF infants gained more weight and lean body mass per gram protein intake but not per megajoule intake. Although growth differences between groups were related to differences in intake, there is no evidence of any functional advantage to the more rapid growth of FF infants.