Background: Behaviour supports plans (BSP), if accurately implemented, have been found to increase skills and decrease behaviours that challenge for individuals with intellectual disabilities. However, skills acquired by staff during trainings on BSPs often fail to transfer into effective implementation. The current study aimed to examine barriers and facilitators to BSP implementation. Method: Focus groups were conducted with four staff teams (n = 21) and semi-structured interviews were carried out with each team's respective team leader (n = 4). Thematic analysis, involving inductive and deductive approaches, was used to analyse the data. Results: Environmental context and resources (e.g., compatibility of environment) and social influences (e.g., level of team communication) were the predominant domains impacting on implementation. Conclusion: Findings emphasise the importance of service providers aligning with the core values of positive behaviour support, which acts as a facilitator for effective BSP implementation. These include integral social processes such as collaboration across key stakeholders and person-centred planning.