Personal outcomes-related quality of life provides information about the impact of individualized supports and services that are provided to people with intellectual disability. The Personal Outcomes Scale (POS) is a valid and reliable instrument that measures these outcomes using two parts, self-report and report by others. Based on the POS, the aim of this study is to provide a new psychometric study of the instrument that allows the evaluation of the three principal informers involved in the enhancement of individual’s quality of life: individual with intellectual disability, professional and family member. This approach overcomes the limitations of the POS. For the self-report were involved 529 people with intellectual disability. A professional (N = 522) and a family member (N = 462) separately participated for the report by others versions to assess personal outcomes for each participant. The reliability study provides appropriate values for the first and second order factors with values being higher than .82. The construct validity analysis provides an adjustment of the theoretical model, particularly regarding the assessments from professionals. Results show this instrument is adequate to evaluate personal outcomes and giving the guidelines for making policy and practice decisions.