SUMMARYAims — The aims of the study was to evaluate if environmental factors can influence the effectiveness of therapeutic intervention of subjects with intellectual disabilities. Methods — 46 adolescents and adults with mental retardation, in semi-residential rehabilitative treatment, have been assessed over a 2-years period. The evolution of adaptive functioning over time has been assessed through the AAMD-ABS. The development of the adaptive skills at follow-up has been correlated with socio-economic and cultural factors. Results — Linear regression showed that age of both parents, mother's health status, lack of one parent, SES, and housing conditions, represent significant covariates to predicting evolution of the adaptive functioning; these factors independently influence effectiveness of the therapy from the kind of treatment. Conclusion — The results demonstrate that effectiveness of the therapy can be conditioned from ability to fulfil the needs of the families, through social and supporting programs.Declaration of Interest: none.