This publication is the final report of the PHS evaluation of the Scottish Government's Residential Rehabilitation programme. The evaluation covered the period between January 2021 and March 2026. The primary purpose of the evaluation, and this report, was to explore the impact of the Residential Rehabilitation programme on the way in which residential rehab is organised, how easily it can be accessed and how well it delivers for individuals with substance use issues across Scotland. 'Residential rehabilitation' refers to different models of care offered for the treatment of substance use in residential settings. The lack of robust Scotland-wide baseline data on residential rehab presented a limitation to the evaluation's ability to explore the impact of the programme. The evaluation took a pragmatic approach, working with the best available monitoring data (systematically highlighting limitations) and exploring stakeholders' perceptions of the impact of the programme to date.