This study focused on attachment of foster children by examining factors associated with attachment relationships of children raised from birth by the same parents. The sample included 61 children between 26 to 88 months of age and their foster caregivers. Attachment security and caregiver sensitivity were coded on the basis of, respectively, a home-observation (Attachment Q-Set) and a laboratory procedure (Three boxes). Other measures included caregiver reports of child externalizing and internalizing behavior problems and symptoms of attachment disorder, including inhibited and disinhibited attachment as well as secure base distortions. For a subsample of children, teacher ratings of behavior problems also were available. Foster parent sensitivity was positively associated with attachment security, but only if symptoms of disordered attachment were partialled out. Symptoms of inhibited and disinhibited attachment as well as secure base distortions were positively related to parent reports of externalizing and internalizing behavior problems whereas attachment security was negatively related to teacher reports of externalizing behavior problems. Attachment theoretical tenets appeared valid with foster parent-child relationships, except for children with symptoms of attachment disorder. © 2008 Michigan Association for Infant Mental Health.