Children in out‐of‐home care that demonstrate challenging behaviour are often thought of as ‘attachment disordered’. Our understanding of what this might mean for practice is not well developed. In this study, 92 South Australian stakeholders were interviewed about how they understood extremely challenging behaviour amongst school‐age children in out‐of‐home care. Participants consistently described behaviour as arising from attachment difficulties. Despite this, there were a variety of ways that a child's attachment needs were conceptualized, which appeared to be inconsistent with contemporary attachment theory. Thematic analysis yielded four implicit views about children's attachment: attachment as capacity that is limited, attachment as skill that children can learn and transfer to other relationships, attachment as unachievable for some children and an idealized view of attachment as a close and trusting relationship. These possible misconceptions about attachment and attachment needs and their relationship to the development of challenging behaviour are discussed in terms of attachment informed research and theory. The possible implications for placement practice and policy for children in out‐of‐home care are discussed.