We undertook this study to determine if culturally influenced feeding practices are associated with iron deficiency in infants and toddlers from low-income families. We obtained a dietary survey, illness history, hematocrit, and zinc protoporphyrin-to-heme ratio (ZPP/H) from 35 Southeast Asian children and 73 children of other ethnicities between ages 5 and 30 months. We confirmed iron deficiency by serum ferritin measurement in children with ZPP/H > 80 mmol/mol or evaluated them after a 3-month iron treatment. Sixty percent of the Southeast Asian children had elevated ZPP/H ratios, compared with 14% of children of other ethnicities. Follow-up studies confirmed iron deficiency in 12 of 21 Southeast Asian children with elevated ZPP/H; 75% (eight) of those with confirmed iron deficiency were 24 to 30 months of age. We found that toddler feeding practices differ between Southeast Asians and other ethnic groups. All 17 Southeast Asian toddlers were still bottle fed at their second birthday, compared with 10 of 21 same-age children of other ethnicities. Persistence of bottle feeding after 2 years of age was highly associated with elevation of ZPP/H in Southeast Asian children but not in other children. Clinicians need to be aware of this problem and carefully monitor iron status in children not weaned from the baby bottle by age 2 years. Changes in education practices and policies are needed to prevent iron deficiency from the overintake of cow's milk that results from prolonged bottle feedings in this ethnic group.