Background: This study aims to introduce direct support staff (DSS) working with adults with intellectual disabilities to the Holistic Support Model (HSM) and assess its influence on their perceptions of their professional role. The HSM, grounded in humanistic principles, guides the support process, prioritising autonomy and meaningful living. Method: Using participatory action research, this study used survey data, qualitative analysis of group meetings, and interviews, to assess changes in DSSs' role perceptions after undergoing in-service training on the HSM. Results: DSS exhibited a shift towards a humanistic perspective, gaining clarity on their roles, which reduced frustration. Doubts persist among DSS regarding the applicability of the HSM to all adults with intellectual disabilities. Conclusions: The studies underscore the positive impact of the HSM on DSS, highlighting its potential to enhance DSS practice. It recommends researching the experiences of adults with intellectual disabilities with the HSM.