This study built on attachment theory and previous research in examining the interactional origins of the secure, insecure-resistant, and insecure-avoidant patterns of attachment. Maternal sensitive responsivity, rejection, and activity were the focus of repeated naturalistic observations when infants were 1, 4, and 9 months of age; quality of attachment was assessed at 1 year. Mothers of secure 1-year-olds were observed to be more sensitively responsive at 1 and 4 months and less rejecting at 1 and 9 months than mothers of insecure infants. Mothers of insecure-avoidant infants were more rejecting at 9 months, whereas mothers of insecure-resistant infants were least sensitively responsive and most rejecting at 1 month; the insecure groups were also differentiated on the basis of patterns of change from 1 to 9 months, with mothers of resistant infants becoming less rejecting and mothers of avoidant infants becoming more rejecting relative to other mothers.