This prospective study examined the relation of neonatal sucking to later feeding, postnatal growth, maternal postpartum depression, and feeding practices. Healthy infants of at least 37 weeks gestational age were recruited. At 1 week of age, a strain-gage device was attached to the infant's cheeks during sucking to identify sucking efficiency. Two-hundred and two infants (100 males, 102 females; mean age 39.6 weeks, SD 1.1 weeks) with efficient sucking and 207 (101 males, 106 females; mean gestational age 39.4 weeks, SD 1.2 weeks) with inefficient sucking were identified. Growth was measured at 2, 6, 10, and 14 months. Mothers completed a feeding questionnaire and the Edinburgh Postnatal Depression Scale at the same testing points. While 18 infants (5%) showed a downward shift in growth, their clinical picture did not present as non-organic failure to thrive (NFTT). Inefficient neonatal sucking did not predict postnatal growth, later feeding difficulties, nor maternal feeding practices, but concurrent inefficient feeding did. Maternal depression did not affect feeding practices, infant feeding abilities, nor growth, suggesting that the importance of maternal postpartum depression in association with feeding may be less than previously assumed. The term NFTT, therefore, merits reexamination and a more focused definition.