This prospective study of 4438 infants (0-4 months) examined differences in infant-feeding patterns in relation to the ethnic origin of their mothers, based on the mother's native language: Dutch (87%), Turkish (4%), Moroccan (3%), other European languages (3%), and various other languages (4%). Breastfeeding at birth varied between 75% and 94%. Dutch and Moroccan mothers breastfed for a shorter period (32% and 37% at 4 months, respectively) than did Turkish mothers and mothers with a native European language other than Dutch (47% and 51% at 4 months, respectively; P > .001). Of all mothers, 71% started exclusive breastfeeding at birth, and 21% continued exclusive breastfeeding for at least 4 months. The reasons why mothers discontinued breastfeeding (both exclusive breastfeeding and breastfeeding) were generally infant related. The average weight gain between birth and day 133 was 3.45, 3.87, and 3.69 kg for Dutch, Turkish, and Moroccan infants, respectively. Weight gain was influenced by ethnicity of the mothers and exclusive breastfeeding. © 2008 International Lactation Consultant Association.