Background: Challenging and disruptive behaviour is commonly reported among children placed in the out-of-home care sector. Little is known about how stakeholders in this sector understand or manage challenging behaviour. Method: Ninety-two stakeholders in the South Australian out-of-home care sector were interviewed about their approach to supporting children with challenging behaviour. Participants were teachers, foster carers, child statutory workers, child mental health workers, and residential care workers. These semi-structured interviews were subject to thematic analysis. Results: The analysis revealed several ways of understanding challenging behaviour: behaviour as learnt, behaviour as purposeful, behaviour as a choice, behaviour arising from constant change, behaviour reflecting strong emotions, and behaviour reflecting attachment history. Conclusions: This analysis suggests that professionals seeking to engage in collaborative casework on behalf of children may need to accommodate a range of diverse views about the origin and solution to challenging and aggressive behaviour. The possible implications of these divergent understandings for placement policy and practice are discussed. These apparently disparate frameworks are discussed in terms of their underlying assumptions, and possible "common ground" is identified and highlighted. Explicating the implicit assumptions inherent in others' accounts may provide a "way forward" in more effective work on behalf of children.