and van IJzendoorn, 1997; Isabella, 1995; Thompson, 1997, 1998a). Infants and toddlers are less likely to establish secure attachments with caregivers who are generally detached, intrusive, erratic, or rejecting. The important role of sensitive caregiving in the establishment of secure attachments is compellingly illustrated by a recent intervention that randomly assigned low-income mothers of infants who were observed in the first two weeks of life to be irritable to a program designed to enhance maternal sensitivity and responsiveness or to a control group. After 9 months, the mothers who had received the programs were significantly more responsive and stimulating than the control group mothers and their infants engaged in more sophisticated exploratory behavior and were significantly more likely to be securely attached (van den Boom, 1994, 1995). A follow-up when the children were 3 ½ years old documented sustained effects in maternal sensitivity, attachment security, and the children's observed cooperation with the mother. Interestingly, the husbands of mothers who participated in the intervention were also more responsive to their preschoolers. Adoption studies add to the evidence regarding the importance of sensitive, responsive care. Toddlers fostered or adopted from conditions of extreme neglect have been found to reorganize their attachment behavior over time, exhibiting behavior reflective of secure expectations of support and comfort as they adapt to foster or adoptive parents who provide sensitive, responsive, and consistent care (Chisholm, 1998; Dozier, in press a, in press b; O'Connor et al., 1999).
Providing sensitive, responsive, and consistent parenting of infants and toddlers is challenging work. Both characteristics of the child and of the parent can make this type of parenting difficult to achieve. For example, newborns who continue to react to repeated stimuli after other newborns have tuned out or habituated to the repeated stimulation are somewhat more likely to form insecure attachment relationships to caregivers (Warren et al., 1997). Babies who become disorganized when stressed and those who get very upset when limits are placed on their actions are also somewhat more likely to develop insecure attachments (Fox, 1985; Gunnar et al., 1996; Izard et al., 1991). These infant characteristics don't predestine children to insecure attachment; rather they shift the odds. This may be because it is harder for people to provide the sensitive parenting such children need. It may be because it is not clear what the baby needs or because the needs of such infants exceed the time, attention, and sensitivity that the parents can provide given all of the demands on them. Indeed, when parents can manage to maintain high degrees of sensitivity and responsiveness, even temperamentally difficult infants develop secure and trusting relationships (Goldberg, 1990; Mangelsdorf et al., 1990; van IJzendoorn et al., 1995). Challenging parental life circumstances can also result in an imbalance between the infant's needs and what the parent can