This study analyzes the quality of life for a sample of 285 institutionalized adults with intellectual disabilities. Quality of life, as assessed by professionals, is conceptualized according to the eight domains model from Schalock and Verdugo. The study also offers evidence of the adequacy (reliability and validity) of the Cross-cultural Measure of Quality of Life Indicators for use with this population. The results revealed significant differences in importance and use of the different dimensions of quality of life, and evaluation ratings of quality of life, based on the degree of disability of the participants. Length of institutionalization significantly impacted on ratings of importance of the different domains of quality of life. Discussion on further research on perceptions of service providers concerning the quality of life of its users and the impact of institutionalization is included.