Background: The current study explored the perspectives of staff working with adults with intellectual disabilities and behaviours that challenge. We sought insight into their understanding of procedural fidelity and challenges faced when implementing behaviour support. Method: We interviewed 15 staff members supporting adults with intellectual disabilities in residential settings. Participants included five front-line staff, five residential managers, and five clinicians. Interviews were transcribed and thematic analysis conducted. Results: Issues identified by the participants related to four main themes: (1) Organisational and environmental constraints; (2) Understanding and monitoring of procedural fidelity; (3) Theory versus practice; (4) There's nothing positive about behaviour support. Conclusion: Across staff groups, lack of understanding of fidelity emerged, as well as minimal accountability regarding behaviour support. Front-line staff felt isolated and under pressure. Greater emphasis on partnership, practice leadership, and positive feedback may give front-line staff the support needed to use behavioural interventions with high fidelity.