["Journal of Applied Research in Intellectual Disabilities, Volume 39, Issue 3, May 2026. ", "\nABSTRACT\n\nBackground\nIndividuals with intellectual disability and severe challenging behaviour (CB) often need intensive support. The present study examines whether mental health classification (MHC) makes interventions aimed at improving quality of life (QoL) more effective.\n\n\nMethod\nA three‐year follow up of 122 men and 62 women with intellectual disability and severe CB, aged 18–70 years, compared number and type of support goals and development of QoL (San Martin Scale) and CB (Developmental Behaviour Checklist for Adults) of individuals with (N = 124) and without (N = 60) MHC.\n\n\nResults\nMHC was associated with setting more support goals. This had no differential effect on the development of QoL or CB. Improvement in QoL was associated with lower initial QoL, higher cognitive functioning and a lower number of support goals set.\n\n\nConclusion\nMHC was not related to better outcomes. Overall, setting fewer support goals and higher cognitive functioning are positively related to the effectiveness of treatment.\n\n"]