Study aims: To assess quality of life and self-concept, and to analyse the relation between these variables during adolescence. Participants: 1121 secondary school students between 12 and 18 Years of age, 151 of whom had special educational needs (SEN). Instruments: Questionnaire to assess the quality of life of adolescents {Cuestionario de Evaluacion de la Calidad de Vida de alumnos adolescentes (Gomez-Vela, 2004)), and the AF5 Self-concept Questionnaire (Cuestionario de Autoconcepto AF5 (Garcia and Musitu, 1999)}. Main results and conclusions: (I) The participants obtained high scores both in quality of life and self-concept. Nevertheless, there were significant differences related to gender, age, and the presence of SEN. Boys obtained lower scores in the academic sphere, while girls did so in the emotional sphere. Younger students got lower scores in Self-determination, SEN was found to affect students' Academic Self-concept, Personal Development, Physical Well-being and Self-determination. (2) Self-concept plays an important role in quality of life during adolescence, specially, with respect to Family, Academic and Physical self-concept.