Intellectual disability affects different aspects of functioning and quality of life, as well as the ability to independently assess the quality of life itself. The paper examines the agreement in the quality of life assessments made by adolescents with intellectual disability and their parents compared with assessments made by adolescents without intellectual disability and their parents. Participants included 67 adolescents with intellectual disability and the same number of their parents. Control group consisted of 122 typically developed adolescents and an equal number of their parents. In order to assess the quality of life we used The PedsQL 4.0 Generic Core Scale questionnaire, for adolescents aged between 13 and 18 and their parents. Agreement in assessing quality of life between adolescents and parents was analyzed using t-test, Kappa Statistics and Pearson correlation. The agreement between adolescents with intellectual disability and their parents was found to be acceptable (k = 0.43), while the agreement between adolescent from control group and their parents was judged to be good (k = 0.84). Correlations between adolescents with intellectual disability and their parents varied across subscales from weak (r = 0.31) on the physical health subscale to moderate (r = 0.56) on the social subscale. Adolescents with intellectual disability were less satisfied with their social functioning. The highest agreement, as well as the lowest means value was found on the social agreement scale. Assessment of the quality of life by both adolescents and their parents provides a comprehensive insight into functioning and different aspects of quality of life in these adolescents. (Contains 3 tables.)