Children of adolescent mothers are at risk for a variety of developmental difficulties. In the present study, the effectiveness of a brief intervention program designed to support adolescent mothers' sensitivity to their infants' attachment signals was evaluated. Participants were adolescent mothers and their infants who were observed at 6, 12, and 24 months of age. The intervention conducted by clinically trained home visitors consisted of eight home visits between 6 and 12 months in which mothers were provided feedback during the replay of videotaped play interactions. At 12 months, 57% of the mother–infant dyads in the intervention group and 38% of the comparison group dyads were classified as secure in the Strange Situation. Seventy-six percent of the mothers in the intervention group maintained sensitivity from 6 to 24 months compared with 54% of the comparison mothers. Further analyses indicated that the intervention was effective primarily for mothers who were not classified as Unresolved on the Adult Attachment Interview.