Sibling unity during family transitions is considered a protective factor for child behavior problems, but there is little empirical support for the widespread child protection policy of placing siblings together in foster care. In a prospective study of 156 maltreated children, siblings were classified in 1 of 3 placement groups: continuously together (n = 110), continuously apart (n = 22), and disrupted placement (siblings placed together were separated; n = 24). Changes in child adjustment as a function of sibling relationship and placement group were examined. Sibling positivity predicted lower child problems at follow-up (about 14 months later), while sibling negativity predicted higher child problems. Placement group did not affect child behavior problems at follow-up; however, compared to siblings in continuous placement (either together or apart), siblings in disrupted placement with high initial behavior problems were rated as having fewer problems at follow-up, while siblings in disrupted placement with low initial behavior problems were rated as having more problems at follow-up. These findings highlight the importance of considering relationships between siblings and the risk that one poses to another before early placement decisions are made.