The relationship between duration of breastfeeding in the first 12 weeks after birth, characteristics of mothers' and infants' behaviors, and the mother's perception of her infant were studied in primiparous mothers and their low-risk newborn infants. 50 women completed questionnaires on infants' temperament, caregiving flexibility, and perception of breastfeeding in their third trimester of pregnancy and again when their infants were 12 weeks old. 30 of the 50 women and their infants were observed for two hours on each of three different occasions at their homes when infants were 2, 6, and 12 wk. of age. Higher rates of mothers' interactive behaviors with their infants, mothers' self-reported perceptions that their infants had "easy" temperaments, and mothers' self-reported flexibility of caregiving were directly correlated with longer duration of breastfeeding and later weaning from the breast.