This study investigated the development of attachment relationships in 38 foster infant-caregiver dyads over the first 2 months of placement. We used the Parent Attachment Diary to measure foster infants' daily attachment behaviors, the Adult Attachment Interview to examine foster parents' attachment states of mind, and Ainsworth's Strange Situation to capture attachment classifications. We examined differences in diary scales (secure, avoidant, resistant, and coherence) as they related to age at placement and foster parent attachment, using hierarchical linear modeling and analyses of variance. The results indicated infants with autonomous foster parents and infants placed at younger ages showed higher early and overall levels of secure behavior, less avoidant behavior, and more coherent attachment strategies compared to infants placed with nonautonomous foster parents. Changes in attachment behaviors over time were not predicted by the models; however, there was a significant decrease in the daily coherence of attachment behaviors associated with Strange Situation disorganization. Finally, we found significant concordance between the diary and Strange Situation scales for secure and avoidant behaviors.